CPACC Quick Reference

Disability is seen as a health condition that affects an individual's body. It's considered a problem of diagnosis, treatment, and, if possible, cure.

A clinician assessing a person in a wheelchair focuses on the underlying diagnosis. Then they consider what medical intervention might restore mobility.

The medical model isn't wrong about biology. But it's limited to treating the person's body as the only site of the problem. It ignores inaccessible environments and social barriers.

Disability is created by the gap between a person's body or mind and an environment that wasn't designed to include them. The barrier is in the world, not the person.

A wheelchair user isn't disabled by their legs. They are disabled by buildings with stairs and no ramps. Remove the stairs, and the disability largely disappears.

Critics argue that the social model downplays the real limitations caused by impairments. They assert that not every barrier is architectural or attitudinal.

Disability comes from a mix of health issues, personal experiences, and social or physical environments. It is biological, personal, and contextual.

The model shows how these three factors work together to produce functional outcomes. The World Health Organization (WHO) used this model to develop its ICF framework. ICF is an abbreviation of the International Classification of Functioning, Disability and Health.

This model supports the ICF framework. Understanding this link explains why the ICF is seen as more complete than just medical or social views.

Disability means reduced ability to work and earn money, which can make a person a cost to productivity and welfare systems.

Insurance and benefits systems often define disability based on how much a condition hinders work. Someone who can work part-time is assessed differently from someone who can't work at all.

This model influences policy and funding decisions. It often views disability as an economic burden rather than a matter of participation and rights.

Disability is a practical issue that technology and design can address. The goal is to provide functional solutions, not to debate the cause of the barrier.

An engineer creating a screen reader isn't questioning if blindness is a medical or social issue. They are building a tool for independent access to information.

This model drives much of the development of assistive technology. It is useful, but it can depoliticise disability by treating it as a technical challenge and ignoring systemic change.

Disability is a valued part of human diversity and cultural identity. It is not a flaw to fix but a trait that influences experiences and communities.

Many Deaf people do not see deafness as a disability. They belong to a linguistic and cultural community linked by sign language, shared history, and unique norms.

The Deaf community is a prime example, but the model also appears in autistic self-advocacy. Not everyone with a condition is identified in this way, and views differ widely.

Disabled people are often seen as objects of pity who rely on the kindness of non-disabled individuals. Support is viewed as generosity rather than a right.

Fundraising campaigns sometimes depict disabled children as tragic figures needing rescue. This is an example of the charity model at work.

Disability rights advocates criticise this view. They argue that it presents disabled people as passive recipients, not as citizens with rights. Yet, this perspective remains common in public messaging and fundraising.

Visual disabilities include:

• A complete absence of vision
• Partial sight
• Colour perception differences.

Each condition has distinct access implications.

Blindness

A person who is blind receives no functional visual information. They rely on non-visual means to access content and navigate the environment.

A blind person using a computer depends on a screen reader to convert text into speech or Braille output. Any visual information must have a text alternative for the assistive tools to be useful.

Legal and medical definitions of blindness vary. "Legally blind" often includes people with some residual vision. In accessibility practice, assume that a screen reader user may have no usable vision.

Low Vision

A person with low vision has partial sight that cannot be fully corrected by glasses or surgery. They may use their vision alongside assistive tools, often with significant magnification.

Someone with low vision might enlarge the text in their browser to 300%. They might also use high contrast mode or rely on a screen magnifier. They often use both vision and technology simultaneously, making layout and spacing critical.

Many low vision users do not use screen readers at all. Visual presentation matters more for this group.

Colour Vision Deficiency

Colour vision deficiency reduces the ability to distinguish between certain colours. The most common form impacts red-green discrimination. But this condition exists on a spectrum.

A chart with only red and green lines is hard to read for those with red-green colour vision deficiency. Adding distinct line patterns or labels solves the problem.

Colour vision deficiency is far more prevalent than most designers assume. It affects approximately 8% of men of Northern European descent. It is not the same as seeing only in grey tones. Most people with CVD see colour, but not as someone without the deficiency does.

Auditory disabilities include:

• Total deafness
• Partial hearing loss
• Differences in auditory processing

Each of these conditions requires different access strategies.

Deafness

A person who is deaf has no functional hearing. They can only understand audio content through visual options, such as captions, transcripts, or sign language interpretation.

A deaf person watching a video without captions receives no audio. Dialogue, sound effects, and tone of voice are all inaccessible unless provided in text or visual form.

Many Deaf people (with a capital D) identify with Deaf culture. They may prefer sign language over written text. For some, reading in a written language is a second-language skill, so captions alone may not be enough.

Hard of Hearing

A person who is hard of hearing has some degree of hearing loss. They may use residual hearing combined with hearing aids, captions, or other strategies.

In a meeting room with poor acoustics, a person with hearing aids may miss critical dialogue. A loop system or real-time captions gives them equal access to the conversation.

Central Auditory Processing Disorder

Central auditory processing disorder (CAPD) affects how the brain interprets sound. While the ear works normally, the person struggles to discern speech. This is especially true in noisy environments.

A person with CAPD in a busy café may hear someone talking but be unable to decode what is being said.

CAPD is easily overlooked because the person "passes" a standard audiological test. Their difficulty is neurological, not peripheral. They are often misunderstood as being inattentive or having a language difficulty.

Deaf-blindness is the combination of both hearing and vision loss. But it is more than the sum of its parts. Since neither sense fully compensates for the loss of the other, unique barriers to communication arise. People who are deaf-blind need tactile communication and other accessible channels.

A person who is deaf-blind may use a refreshable Braille display connected to a screen reader. Text is the only format that reaches them. So, alt text, captions, and transcripts are all essential, not supplementary.

Most people identified as deaf-blind have some residual vision or hearing. Complete absence of both senses is uncommon. Further, deaf-blindness exists on two separate spectra. So, the degree of loss in each sense determines the specific access needs.

Speech and language disabilities affect the ability to produce or process spoken language — they range from articulation differences to complete absence of speech, and they create barriers in voice-reliant systems and communication contexts.

Organic Speech Sound Disorders

Organic speech sound disorders have a physical cause — structural differences, neurological conditions, or sensory impairments that affect how speech sounds are produced.

A person with dysarthria caused by cerebral palsy may have speech that is difficult to understand — voice recognition software trained on typical speech patterns will fail to recognise their input reliably.

⚠️ "Organic" indicates there is an identifiable physical cause — this distinguishes these disorders from functional speech sound disorders where no structural cause is found.

Functional Speech Sound Disorders

Functional speech sound disorders affect articulation or phonological processing without an identifiable organic cause — speech sounds are substituted, omitted, or distorted in ways that may or may not resolve over time.

A child who consistently substitutes "w" for "r" (saying "wabbit" for "rabbit") has a functional articulation disorder — their speech mechanism is intact but the learned production pattern differs from the target.

No Speech (Mutism)

Mutism is the absence of speech — it may be selective (speech occurs in some contexts but not others) or total, and may have psychological, neurological, or other origins.

A child with selective mutism speaks freely at home but produces no speech at school — augmentative and alternative communication tools, such as a tablet with symbol-based output, can give them a way to participate.

⚠️ Selective mutism is an anxiety-based condition, not a choice or defiance — people with selective mutism are often fully capable of speech in other contexts and should never be assumed to have cognitive or language difficulties.

Aphasia

Aphasia is an acquired language disorder — typically from stroke or brain injury — that can affect speaking, understanding, reading, and writing in any combination.

A person with Broca's aphasia knows what they want to say but cannot produce fluent speech — they may communicate in single words or short phrases while their comprehension remains relatively intact.

⚠️ Aphasia affects language, not intelligence — a person with severe aphasia may have full cognitive capacity but be unable to express it through speech or writing. This distinction matters enormously for how people are treated and supported.

Mobility and body function disabilities affect movement, physical control, and bodily function — they create barriers in environments and interfaces designed for a standard range of physical ability.

Manual Dexterity and Fine Motor Control

Difficulties with manual dexterity and fine motor control affect the precise hand and finger movements needed to use a standard keyboard, mouse, touchscreen, or small physical controls.

A person with Parkinson's disease may find it impossible to accurately click small interface targets or type reliably with a standard keyboard — switch access, voice control, or larger touch targets restore independent access.

⚠️ Fine motor difficulties are often invisible — a person may appear unimpaired until they attempt a task requiring precision. Many users of keyboard navigation and switch access have fine motor, not visual, disabilities.

Ambulation

Ambulation disabilities affect the ability to walk or move through space — they range from conditions requiring mobility aids to complete inability to walk.

A wheelchair user approaching a building entrance blocked by steps cannot enter — a ramped or level entrance gives everyone the same access without requiring a detour or assistance.

Muscle Fatigue

Muscle fatigue disabilities cause the muscles to tire rapidly or unpredictably — the person may be able to perform a task initially but becomes unable to sustain it.

A person with multiple sclerosis may be able to type for short periods but experiences increasing weakness with sustained use — keyboard shortcuts, voice input, and tasks requiring fewer keystrokes reduce the physical load.

⚠️ Fatigue-related disabilities are episodic and variable — a person's ability on one day may not reflect their ability on another. Designing for efficiency and reducing repetitive actions benefits this group significantly.

Body Size or Shape

Body size or shape differences — including very short stature, limb differences, or atypical body proportions — create barriers in environments and products designed around a narrow assumed body range.

An ATM positioned at a height accessible to standing adults is unreachable from a seated position or for someone of very short stature — height-adjustable or lower-mounted controls address this.

⚠️ Body size and shape are often overlooked in discussions of disability and accessibility — the principles of universal design address this explicitly, particularly through the "Size and Space for Approach and Use" principle.

Cognitive disabilities affect how people process, understand, remember, and communicate information — they are among the most diverse category of disability and among the most underserved by mainstream accessibility practice.

Intellectual Disabilities

Intellectual disabilities involve significant limitations in cognitive functioning and adaptive behaviour — they affect learning, reasoning, problem-solving, and the ability to manage everyday tasks independently.

A person with an intellectual disability using a government benefits portal may struggle with complex sentence structures, abstract terminology, or multi-step processes — plain language, clear instructions, and simplified workflows directly expand their access.

⚠️ "Intellectual disability" is the preferred current terminology over older terms such as "mental retardation" — terminology in this area has changed significantly and precision matters professionally.

Reading and Dyslexia

Dyslexia is a specific learning disability that affects accurate and fluent word reading and spelling — it is neurological in origin, unrelated to intelligence, and affects people across the full cognitive spectrum.

A highly intelligent adult with dyslexia may read slowly, lose their place frequently, or confuse visually similar letters — text-to-speech, adjustable line spacing, and dyslexia-friendly fonts reduce the cognitive load of reading.

⚠️ Dyslexia is not a vision problem — the letters are not literally moving or reversed. It is a phonological processing difference that makes it harder to decode written symbols into spoken language units.

Math and Computation (Dyscalculia)

Dyscalculia is a specific learning disability affecting the ability to understand numbers, perform calculations, and process mathematical concepts — it is the numerical equivalent of dyslexia.

A person with dyscalculia may be unable to reliably tell which of two prices is larger, or struggle to count change at a checkout — presenting totals clearly and avoiding reliance on mental arithmetic improves access.

Attention Deficit Hyperactivity Disorder (ADHD)

ADHD is characterised by persistent patterns of inattention, hyperactivity, and impulsivity that interfere with functioning — it affects the ability to sustain focus, organise tasks, and regulate behaviour.

A person with ADHD trying to complete a long online form may lose focus partway through, miss required fields, or be distracted by animations and moving content — reducing distractions and saving progress automatically supports task completion.

⚠️ ADHD presents differently across individuals and contexts — inattentive presentations (without hyperactivity) are often missed, particularly in women and girls, and may be mistaken for disengagement or low motivation.

Autism Spectrum Disorders

Autism spectrum disorders affect social communication, sensory processing, and behavioural flexibility — the presentation varies enormously, and access barriers are as likely to be sensory or communicative as cognitive.

An autistic person may be overwhelmed by autoplay audio, flashing animations, or unpredictable interface changes — consistent, predictable design with user control over sensory elements reduces distress and supports access.

⚠️ Autism is a spectrum — some autistic people have high support needs, others are fully independent. "High-functioning" as a term is contested within the autistic community because it tends to dismiss support needs while masking ability.

Non-Verbal Learning Disability

Non-verbal learning disability (NVLD) affects the ability to interpret non-verbal information — spatial reasoning, patterns, facial expressions, tone of voice, and visual-spatial tasks are characteristically difficult.

A person with NVLD may excel at reading and verbal tasks while struggling with maps, diagrams, or inferring meaning from charts — replacing or supplementing visual-spatial content with clear verbal explanations improves access.

⚠️ NVLD is often described as the "inverse of dyslexia" — strong verbal skills can mask the disability, leading to it being underidentified, especially when academic success in verbal subjects suggests no difficulty.

Seizure disorders involve episodes of abnormal electrical activity in the brain — the type and trigger of seizures determine what access barriers are relevant in digital and physical environments.

General Seizure Disorders

General seizure disorders can produce a range of episodes — from brief absences to convulsions — without necessarily being triggered by environmental stimuli.

A person with generalised epilepsy may experience a tonic-clonic seizure without any warning or specific trigger — their access needs relate more to physical safety, reliable communication, and avoiding cognitive overload than to specific content restrictions.

Photosensitive Epilepsy

Photosensitive epilepsy is triggered by flashing or flickering visual stimuli — content that flashes more than three times per second can provoke a seizure in susceptible individuals.

An animated advertisement flashing rapidly on a news website could trigger a seizure in a person with photosensitive epilepsy — this is why accessibility guidelines set specific thresholds for flash frequency and restrict certain patterns.

⚠️ Photosensitive epilepsy affects a small percentage of people with epilepsy — but when it does trigger a seizure, the consequence is immediate and serious. This is one of the few accessibility failures that can cause direct physical harm.

Psychological disabilities affect mental health and behaviour in ways that can create barriers to participation — they are often episodic, variable, and invisible, and are frequently underrepresented in accessibility discussions.

Anxiety Disorders

Anxiety disorders involve persistent, disproportionate fear or worry that interferes with daily functioning — they can make unfamiliar, complex, or high-stakes digital tasks significantly more difficult.

A person with severe social anxiety may be unable to complete a task that requires real-time interaction or phone contact — offering asynchronous or text-based alternatives reduces the barrier without requiring the person to disclose their condition.

⚠️ Anxiety disorders are the most prevalent mental health conditions globally — design decisions that create uncertainty, unclear error recovery, or high-stakes irreversible actions disproportionately affect people with anxiety.

Mood Disorders

Mood disorders — including depression and bipolar disorder — affect motivation, energy, concentration, and the ability to sustain tasks over time.

During a depressive episode, a person may struggle to complete multi-step processes, retain information between sessions, or engage with dense text — saving progress, reducing cognitive load, and allowing tasks to be resumed easily all help.

⚠️ The episodic nature of mood disorders means a person's functional capacity varies — a design that works for them during a period of wellness may not work during an episode. Progressive disclosure and low-effort pathways provide resilient access.

Psychotic Disorders

Psychotic disorders — including schizophrenia — can affect perception, thinking, and the ability to distinguish reality from internal experience, with significant impacts on the ability to navigate complex or confusing environments.

A person experiencing a psychotic episode may misinterpret unclear interface messages, have difficulty filtering relevant from irrelevant content, or struggle to follow multi-step instructions — clear, literal language and predictable interfaces reduce cognitive confusion.

⚠️ Psychotic disorders are among the most stigmatised disability categories — accessibility discussions rarely include them explicitly, yet the same cognitive accessibility principles that support people with intellectual disabilities and dementia also benefit this group.

Many people live with more than one disability simultaneously — when conditions co-occur, the combined access barriers can be greater and more complex than either disability alone would suggest.

AT for visual disabilities substitutes or supplements visual information — through touch, audio, or enhanced visual presentation — to give people independent access to content and environments.

Physical Environment

In the physical world, AT for visual disabilities includes tools that provide tactile or audio information in place of visual cues.

A person who is blind uses a long cane to detect obstacles while walking and relies on tactile paving strips at pedestrian crossings to identify safe crossing points — these are physical environment AT solutions.

⚠️ Guide dogs are widely recognised AT but are not always available or appropriate — physical environment solutions must not assume a guide dog as the primary access strategy.

ICT Environment

In the ICT environment, AT for visual disabilities includes screen readers, screen magnifiers, braille displays, and high contrast or colour adjustment settings.

A blind person uses a screen reader such as NVDA or JAWS to hear a text-to-speech rendering of web content, while a person with low vision uses built-in magnification to enlarge the display to a usable size — both rely on the underlying content being structured accessibly.

⚠️ Screen readers and magnifiers are both AT for visual disabilities but they interact with content very differently — a page can be magnifier-friendly and still be a screen reader failure if the semantic structure is absent.

AT for auditory disabilities amplifies, supplements, or replaces audio information — through amplification systems, visual alerts, and text-based alternatives to spoken communication.

Physical Environment

In the physical world, AT for auditory disabilities includes hearing loops, visual alert systems, and real-time captioning services.

A theatre fitted with an audio induction loop transmits sound directly to a hearing aid or cochlear implant set to the T-coil position, cutting out background noise and giving the person direct access to the performance.

⚠️ Hearing loops are only useful to people wearing compatible hearing devices — they do not help people who are deaf and do not use a hearing aid, who need visual or tactile solutions instead.

ICT Environment

In the ICT environment, AT for auditory disabilities includes captions, transcripts, sign language interpretation in video content, and visual or haptic notification systems.

A deaf person watching a video conference uses real-time captions generated by automatic speech recognition or a live captioner — without captions, all spoken content is inaccessible regardless of the quality of the video.

⚠️ Automatic captions vary significantly in accuracy and are particularly poor for accented speech, technical vocabulary, and poor-quality audio — they are a starting point, not a reliable substitute for human-reviewed captions.

AT for deaf-blindness routes information through the tactile sense — both for environmental navigation and for accessing digital content — since neither vision nor hearing is available as a primary channel.

Physical Environment

In the physical world, AT for deaf-blindness includes tactile communication systems and support from intervenors who relay environmental information through direct contact.

A deaf-blind person using the hand-over-hand signing method has a support worker sign directly into their palm — this tactile form of sign language conveys spoken communication that neither sight nor hearing can reach.

⚠️ Many deaf-blind people rely on specialist intervenors — trained human intermediaries — for access to the physical world. This human dependency is a significant equity issue when such support is unavailable.

ICT Environment

In the ICT environment, AT for deaf-blindness is primarily the refreshable braille display — a device that renders screen reader output as tactile braille characters that change dynamically as content changes.

A deaf-blind person reads a web page by running their fingers across a refreshable braille display connected to a screen reader — the display outputs one line of braille at a time, updated as they navigate through the content.

⚠️ Refreshable braille displays are expensive and require text-based content — they cannot convey images, and any content that is only visual (charts, infographics) must have meaningful text alternatives to be accessible at all.

AT for mobility and body function disabilities replaces or supports physical movement — in the environment, this means mobility aids; in ICT, it means alternative input methods that don't require precise hand or body control.

Physical Environment

In the physical world, AT for mobility disabilities includes wheelchairs, walkers, prosthetics, and powered mobility devices that extend or replace the person's own physical movement.

A person with spinal cord injury uses a powered wheelchair to navigate buildings independently — the wheelchair is only effective AT if the built environment provides ramps, wide doorways, and accessible lifts.

⚠️ Mobility AT extends ability only as far as the environment allows — a powered wheelchair is useless against a flight of stairs. AT and accessible design must work together; one without the other is insufficient.

ICT Environment

In the ICT environment, AT for mobility disabilities includes alternative keyboards, switch access devices, eye-tracking systems, voice recognition software, and mouth or head sticks.

A person with quadriplegia uses an eye-tracking system to control a computer cursor by looking at targets on screen — every interface element they need to activate must be large enough and spaced sufficiently for reliable gaze targeting.

⚠️ Voice recognition is AT for mobility disabilities as much as it is a general convenience feature — people who use it out of necessity (not preference) are disproportionately affected when microphone access is blocked or voice control is poorly implemented.

AT for cognitive disabilities supports memory, comprehension, organisation, and task completion — tools in this category extend what the person can do by compensating for cognitive processing differences.

Physical Environment

In the physical world, AT for cognitive disabilities includes visual schedules, reminder systems, wayfinding aids, and simplified signage that reduce cognitive demands in navigating daily life.

A person with an intellectual disability using public transport relies on clearly illustrated stop-by-stop maps and audible stop announcements — text-only or complex navigational signage creates a barrier even though the physical infrastructure is accessible.

⚠️ Cognitive AT in the physical environment is often overlooked in favour of motor and sensory access — but for people with intellectual disabilities, a building that is physically navigable can still be cognitively inaccessible.

ICT Environment

In the ICT environment, AT for cognitive disabilities includes text-to-speech tools, reading aids, spellcheckers, word prediction software, and focus tools that reduce distraction.

A student with dyslexia uses a text-to-speech application to have web page content read aloud while following along visually — word prediction software reduces spelling demands when they write, enabling them to communicate more fluently.

⚠️ Cognitive AT is the least standardised and most diverse category — unlike screen readers, there is no single dominant tool. Many cognitive AT users rely on a combination of built-in OS features, browser extensions, and specialist applications.

AT for seizure disabilities focuses on preventing seizure triggers and managing safety — in ICT environments, this means tools and settings that suppress harmful visual content before it reaches the user.

Physical Environment

In the physical world, AT for seizure disabilities includes seizure alert devices, protective headgear, and medical alert identifiers that improve safety during and after a seizure episode.

A person with epilepsy wears a medical alert bracelet so that first responders know not to restrain them during a tonic-clonic seizure — this is low-technology AT that can be critical in an emergency.

ICT Environment

In the ICT environment, AT for seizure disabilities includes browser extensions and operating system settings that detect and block flashing or rapidly changing visual content before it is rendered.

A browser extension for photosensitive users can automatically pause animated GIFs and flag pages containing high-frequency flash content — reducing exposure risk when content creators have not followed accessible design practices.

⚠️ AT cannot fully compensate for inaccessible content in this area — a seizure can occur before the user has any opportunity to activate a safety tool. Accessible design at the content level (not relying on the user to self-protect) is essential.

AT for psychological disabilities supports focus, reduces anxiety, and helps manage task demands — tools in this category often overlap with cognitive AT and are used to regulate mental load and emotional responses during digital interactions.

Physical Environment

In the physical world, AT for psychological disabilities includes sensory tools, structured schedules, and environmental modifications that reduce distress and support regulation.

A person with severe anxiety disorder uses noise-cancelling headphones and a structured task list when working in a shared office — reducing unpredictable sensory input and cognitive uncertainty lowers the baseline stress that makes tasks harder to complete.

ICT Environment

In the ICT environment, AT for psychological disabilities includes focus mode tools, content blocking extensions, and apps that reduce cognitive and emotional overload — such as hiding notification counts or limiting distracting content.

A person with PTSD uses a content warning browser extension to blur or hide potentially distressing images before they appear — this gives them agency over their exposure rather than requiring them to avoid the web entirely.

⚠️ AT for psychological disabilities is the category most dependent on the person being able to anticipate and configure their own environment in advance — this creates a significant barrier for people who are in an acute episode and cannot engage with setup tasks.

Users must be able to receive information through at least one of their senses. Content that exists only in one format — only visual, or only audio — is invisible to some users.

⚠️ Perceivable is about the user receiving the content, not about the content being technically present. A video that includes audio description is perceivable to blind users; the same video without description is not.

Text Alternatives

Any content that is not text must have a text alternative that serves the same purpose.

A photo of a product on a shopping site needs alt text that describes what the image shows, not just a file name like "img0042.jpg", so a screen reader user gets the same information as a sighted user.

Time-based Media

Audio and video content needs alternatives so users who cannot hear or see the media can access the same information.

A recorded lecture needs captions for deaf users and an audio description track for blind users who cannot see what is happening on screen.

Adaptable

The meaning must survive when the presentation changes.

A table that looks organised on screen can become a jumble of disconnected words when read aloud by a screen reader — because the visual structure was not reflected in the underlying code.

⚠️ "Presentation" is not just visual — it includes any way content is rendered, including audio, braille, and reflow on small screens.

Distinguishable

Content must be easy to separate from the background and from surrounding elements, using tools like colour contrast and the ability to resize text.

Light grey text on a white background may look clean to a designer, but it fails users with low vision or colour vision deficiency who cannot distinguish the text from the page.

⚠️ Colour alone must never be the only way to convey information — for example, using only red and green to show pass and fail states excludes users with red-green colour vision deficiency.

Users must be able to interact with and navigate the interface, no matter what input method they use.

⚠️ Operable covers the full range of how people control technology — keyboard, switch, voice, eye tracking, and more. Designing only for mouse users shuts out a large group of people with motor disabilities.

Keyboard Accessible

All functionality must be available using only a keyboard, because many people with motor disabilities cannot use a mouse.

A user who controls their computer with a single switch steps through page elements using the Tab key. If a dropdown menu only opens on mouse hover, that user cannot access it at all.

Enough Time

Users must be able to complete tasks without being rushed or timed out unexpectedly.

A banking site that logs users out after two minutes of inactivity may work for a quick typist, but a user with a motor disability who types slowly may find their session ends before they finish filling out a form.

Seizures and Physical Reactions

Content must not include flashing or motion that could trigger seizures or cause physical discomfort.

An animated advertisement that flashes rapidly can trigger a photosensitive epileptic seizure in someone with that condition, even if the user did not choose to view the animation.

Navigable

Users must have ways to find content, know where they are, and move through pages efficiently.

A user who navigates by keyboard uses skip links to jump past the main navigation and go straight to the page content, saving dozens of tab presses on every page they visit.

Input Modalities

Functionality must work with a range of input methods beyond keyboard, including touch and pointer devices.

A mobile interface that requires a complex swipe gesture excludes users who can only tap, such as someone using a single finger due to a hand tremor.

⚠️ Input Modalities was added in WCAG 2.1 to address mobile and touch contexts that the original guidelines did not fully cover — it sits alongside Keyboard Accessible rather than replacing it.

Users must be able to understand both the content and how the interface works.

⚠️ Understandable is the most human of the four principles — it requires thinking about cognition, language, and predictability, not just technical implementation.

Readable

Text content must be readable and understandable, including declaring the language of the page so assistive technologies can use the right pronunciation rules.

A screen reader set to English will mispronounce French words unless the HTML declares that a passage is in French, leaving the user hearing garbled audio that does not convey the meaning of the text.

Predictable

Pages and components must behave in ways that users expect, without surprising changes of context.

If selecting an option in a dropdown automatically submits a form and loads a new page, a user who is exploring options by pressing arrow keys may trigger an action they did not intend and cannot easily undo.

Input Assistance

When users make errors in forms, the interface must help them identify and fix those errors.

A checkout form that just turns an invalid field border red gives no information to a screen reader user about what went wrong or how to fix it. A clear error message in text, linked to the relevant field, serves all users.

Content must be built to a standard that current and future user agents, including assistive technologies, can reliably interpret it.

A custom-built interactive widget that works visually but uses no standard HTML roles or ARIA attributes will be completely invisible to a screen reader, because the assistive technology has no way to understand what the widget is or how to interact with it.

⚠️ Robust is future-facing as well as present-facing. Content built on web standards is more likely to work with assistive technologies that do not exist yet, not just with those available today.

The design must be useful and appealing to people with a wide range of abilities, providing the same means of use for everyone where possible, and equivalent means where identical use is not achievable.

A building entrance with only steps at the front forces wheelchair users to find a separate side entrance. A ramped entrance that everyone uses is equitable; a hidden rear ramp is not.

⚠️ Equitable use means that no group is stigmatised or segregated by the design. A separate "accessible entrance" at the back of a building may meet minimum codes but fails this principle because it singles out and excludes users.

The design accommodates a wide range of individual preferences and abilities, including choice in methods of use and adaptability to the user's pace.

Scissors designed to work with either the left or right hand, and usable at a range of speeds, serve far more people than a standard right-handed pair.

The design is easy to understand regardless of the user's experience, knowledge, language skills, or current level of concentration.

A washing machine with a single dial that shows wash cycles as simple icons works for a new user, an elderly user, or someone reading in a second language, because the design does not depend on technical knowledge or fluency.

The design communicates necessary information to the user effectively, using multiple formats — pictorial, verbal, and tactile — so that it works for people with different sensory abilities.

A pedestrian crossing that uses both an audible tone and a tactile strip on the ground communicates the same "safe to cross" message to users who cannot see the green light and users who cannot hear the tone.

⚠️ Perceptible information is about redundancy across sensory channels, not repetition. Each format conveys the same essential meaning so no single mode is a bottleneck for any user.

The design minimises hazards and the harmful consequences of accidental or unintended actions.

A power saw that requires the user to hold down two buttons simultaneously before the blade activates prevents accidental starts, protecting users who may have reduced hand coordination or slower reaction times.

⚠️ Tolerance for error is not the same as preventing all errors. The principle requires that errors, when they happen, do not cause serious harm — through warnings, fail-safe features, and design that discourages unconscious actions in high-stakes tasks.

The design can be used comfortably and with minimal fatigue, keeping the body in a neutral position and reducing the need for repetitive or sustained effort.

A lever door handle that opens with a light downward push requires far less grip strength and wrist effort than a round knob, making it easier for users with arthritis, limited hand strength, or full hands.

The design provides appropriate size and space for approach, reach, manipulation, and use regardless of the user's body size, posture, or mobility.

A ticket machine with a screen angled toward both standing and seated users, and enough floor space for a wheelchair to pull up alongside it, works for far more people than a machine designed only for a standing adult of average height.

⚠️ This principle explicitly includes space for assistive devices. A space that is technically reachable but leaves no room to manoeuvre a wheelchair or walking frame does not meet the intent of the principle.

The UDL framework is built on three guidelines: providing multiple means of Engagement (the why of learning), Representation (the what of learning), and Action and Expression (the how of learning).

⚠️ UDL is a design framework for educators, not a checklist of disability accommodations. It asks instructors to build in flexibility for all learners before teaching begins, not to respond to individual needs as they arise.

Multiple Means of Engagement

Instructors must offer multiple ways to motivate learners and sustain their effort, because learners differ widely in what engages them and what helps them stay focused and self-regulate.

One student thrives with open-ended, creative tasks while another finds the same tasks overwhelming and needs clear structure and routine. An instructor who offers both options gives each learner a path into the material.

⚠️ Engagement is not just about making learning "fun." It includes helping learners set goals, sustain effort over time, and manage their own emotional responses to challenge — all of which vary across individuals and contexts.

Multiple Means of Representation

Instructors must present information in more than one format, because learners perceive and process content differently depending on sensory ability, language background, and learning style.

A science concept explained only through a dense written passage may be fully clear to a strong reader but opaque to a student with dyslexia. Pairing the text with a labelled diagram and a short spoken explanation gives all learners a way in.

⚠️ Representation is not about simplifying content. It is about providing multiple access points to the same content, so that the format of delivery is not the barrier to understanding.

Multiple Means of Action and Expression

Instructors must give learners more than one way to demonstrate what they know, because people differ in how they can physically interact with materials and how they can best express their understanding.

A student with cerebral palsy may find a written exam impossible to complete in the given time, but can demonstrate the same knowledge through a recorded verbal response. Offering both options removes the format as a barrier to showing competence.

Usability measures how easily a person can use a product to reach their goal. User experience (UX) is broader — it covers every aspect of the interaction, from first awareness through to trust and satisfaction over time.

A site may be technically usable — a screen reader user can navigate it and submit a form — but the experience is poor if error messages are confusing, the layout is inconsistent, and the process feels hostile. Accessibility is necessary for a good UX, but it is not sufficient on its own.

⚠️ Usability and accessibility are related but not the same. A product can be usable for most people but inaccessible to people with disabilities. Good UX design must treat accessibility as a requirement, not an optional add-on.

The Universal Declaration of Human Rights (1948) was the first document to set out fundamental rights that apply to all people everywhere. It forms the foundation on which later disability-specific instruments are built.

⚠️ The UDHR does not name disability as a protected characteristic. People with disabilities are covered by its general human rights provisions, but the absence of explicit mention left a gap that later conventions — particularly the CRPD — were designed to fill.

The CRPD (2006) is the first legally binding international treaty that specifically protects the rights of people with disabilities. It shifts the framing from charity and medical treatment to rights, autonomy, and full participation in society.

⚠️ Signing and ratifying the CRPD are different things. A state that signs expresses intent; a state that ratifies takes on legal obligations. Countries that have ratified must take active steps to implement the rights it describes, not just acknowledge them.

The Marrakesh Treaty (2013) creates a copyright exception that allows people with print disabilities — including blindness and dyslexia — and their organisations to produce and share accessible format copies of published works without needing permission from the rights holder.

⚠️ The Marrakesh Treaty sits at the intersection of copyright law and accessibility. Without it, converting a book into braille or an audio format could technically infringe copyright. The Treaty removes that legal barrier specifically for people with print disabilities.

The Charter of Fundamental Rights of the European Union (2000, legally binding from 2009) consolidates the fundamental rights of everyone living in the EU. It explicitly prohibits disability discrimination and recognises the right of people with disabilities to independence and social participation.

⚠️ The EU Charter sits on top of an earlier layer of European rights law. The European Convention on Human Rights (1950), binding on all Council of Europe members, also covers disability, but only indirectly under "other status" — disability is not named. The Charter is more direct.

The African Charter (1981) protects the rights of all people across African Union member states. Disability is not named in its anti-discrimination provisions, but the Charter has been used to challenge disability discrimination. The African Disability Rights Protocol (2018) adds specific disability protections as a supplement to the Charter.

⚠️ As of 2023, the African Disability Rights Protocol had not yet received the 15 ratifications needed to enter into force. It exists and has been adopted, but it is not yet legally binding on member states.

The Inter-American Convention on the Elimination of All Forms of Discrimination Against Persons with Disabilities (1999) was the first regional binding treaty to directly and explicitly prohibit discrimination based on disability. It requires member states to take concrete steps to remove barriers and promote full social integration.

⚠️ The Inter-American Convention predates the CRPD by seven years, making it a pioneer in binding disability rights law. However, its scope is narrower than the CRPD — it focuses on eliminating discrimination and removing barriers, while the CRPD takes a broader human rights approach.

The UK Equality Act 2010 consolidated several earlier anti-discrimination laws into a single framework. It prohibits discrimination based on a list of protected characteristics, with disability explicitly included, and covers both direct and indirect discrimination as well as discrimination arising from disability.

⚠️ The Equality Act distinguishes between direct discrimination (treating someone worse because of disability), indirect discrimination (a neutral policy that disadvantages disabled people), and discrimination arising from disability (treating someone badly because of something connected to their disability). These are three distinct legal tests, not one.

The ADA is a civil rights law that prohibits discrimination against people with disabilities across employment, public accommodations, transport, telecommunications, and state and local government services. It treats disability discrimination as comparable to discrimination on grounds of race, sex, or religion.

⚠️ The ADA does not include explicit technical standards for digital accessibility. Federal websites are covered by a separate law (Section 508). Private business websites are covered under the ADA's public accommodations title, but enforcement has largely happened through litigation rather than prescribed technical standards.

The Ontarians with Disabilities Act commits the Government of Ontario, and all sectors of Ontario society, to work toward a province where barriers for people with disabilities are identified, removed, and not re-created.

⚠️ The Ontarians with Disabilities Act of 2001 focused mainly on the public sector and was considered limited in scope. It was followed in 2005 by the Accessibility for Ontarians with Disabilities Act (AODA), which extended requirements to the broader private sector and set specific, enforceable accessibility standards. The two acts are related but distinct.

All EU member states have implemented the EU Employment Equality Directive, which prohibits disability discrimination in employment. Beyond employment, member states vary considerably — some prohibit disability discrimination broadly, some require reasonable accommodation, some do both, and some do neither.

⚠️ EU-level harmonisation of disability discrimination law is incomplete. Employment protections are consistent across member states because of the directive, but protections outside employment — in healthcare, education, housing — differ significantly from country to country.

Domain-specific laws address accessibility requirements within particular sectors. They may be designed specifically for accessibility, or they may be broader laws in which accessibility plays a central role. Examples include laws covering air travel, broadcasting, and digital communications.

⚠️ Domain-specific laws sit alongside, not instead of, general anti-discrimination law. A company may be compliant with a sector-specific law and still face discrimination claims under broader legislation — and vice versa.

Procurement laws require government agencies to buy accessible ICT products and services. By making accessibility a condition of government contracts, these laws create market pressure that influences what vendors build, even beyond the public sector.

⚠️ Procurement law is one of the most powerful levers for driving accessibility at scale. When a large public agency requires accessibility in all ICT procurement, suppliers must meet those requirements to compete for contracts — which often means improving their products for all customers, not just government ones.

In the US, Section 508 of the Rehabilitation Act requires federal agencies to make their ICT accessible to employees and members of the public with disabilities. Federal agencies must follow the Section 508 Standards, which reference WCAG for web content. The ADA covers private sector websites through its public accommodations title, enforced mainly through litigation.

⚠️ Section 508 and the ADA are separate legal frameworks with different scopes. Section 508 applies to federal agencies and sets specific technical standards. The ADA applies more broadly but does not prescribe technical standards — courts have interpreted it to require accessibility, but the standard of "what counts" has been determined case by case.

In the EU, the Web Accessibility Directive requires public sector websites and apps to meet accessibility standards. The European Accessibility Act extends requirements into the private sector for key products and services. Both instruments reference EN 301 549, the European standard that itself incorporates WCAG.

⚠️ The Web Accessibility Directive and the European Accessibility Act have different scopes. The Directive covers public sector bodies. The Act covers private sector products and services in specific categories (banking, e-commerce, transport, and others). Neither covers everything — gaps exist, particularly for internal government tools and small enterprises.

The W3C Web Accessibility Initiative provides a structured planning framework for organisations, covering how to initiate, plan, implement, and sustain an accessibility programme. The framework begins with building internal awareness and a business case before moving to implementation.

⚠️ The WAI framework treats accessibility as organisational change management, not just technical work. An organisation that only focuses on fixing code without securing leadership support, raising staff awareness, and setting measurable goals is unlikely to sustain progress.

These guidelines help organisations make their information accessible to everyone, including people with disabilities. They cover a four-stage implementation cycle — Policy, Plan, Practice, and Review — and emphasise that accessible information production must be embedded in normal workflows, not treated as a separate task.

⚠️ The guidelines apply to all information an organisation produces, not just its website. Internal documents, publications, videos, and procurement specifications all fall within scope — a gap many organisations overlook when they focus only on their public-facing digital presence.

Accessibility maturity models give organisations a structured way to measure where they are and track progress over time. They typically describe a scale from ad hoc and unpredictable at the low end to continuous improvement and innovation at the top.

⚠️ No single maturity model is the official standard. The W3C, the Business Disability Forum, and Carnegie Mellon's adapted Capability Maturity Model all offer different frameworks. The right model depends on an organisation's context — what matters is using one consistently rather than which one is chosen.

Accessibility champions are people appointed across an organisation to advocate for accessibility within their teams, build skills and awareness, and sustain momentum between formal accessibility reviews. Without visible internal advocates, accessibility work often stalls when external pressure eases.

⚠️ A management champion is not the same as a technical lead or accessibility specialist. Champions come from all parts of the organisation — HR, legal, marketing, product — and their value is in embedding accessibility thinking into decision-making at every level, not in doing accessibility audits themselves.

Accessibility evaluation must happen early and often across the design and development lifecycle. Finding and fixing issues before launch is far cheaper and easier than retrofitting accessibility after a product ships.

⚠️ Automated tools can find only a portion of accessibility issues — estimates vary, but automated checks typically catch around 30 to 40 percent of problems. Human evaluation, including testing with people who use assistive technologies, is essential and cannot be replaced by tools alone.

Building an accessible organisation requires both recruiting people with disabilities into the workforce and hiring staff with digital accessibility skills. Both goals depend on accessible recruitment processes — if the job application system itself is inaccessible, both aims are undermined from the start.

⚠️ Recruiting for disability inclusion and recruiting accessibility specialists are related but separate activities. An organisation can do both, but conflating them risks treating people with disabilities primarily as a source of accessibility expertise rather than as employees contributing across all roles.

All communications an organisation produces — internal and external, text and video, web and print — must be accessible. This means setting standards, training communicators, captioning videos, and ensuring that published documents meet accessibility requirements.

Inaccessible products and services carry legal risk in jurisdictions where accessibility is a legal requirement, and reputational risk everywhere. Organisations must assess their legal exposure and ensure their accessibility statements are reviewed by legal before publication.

⚠️ Accessibility creates both risk and opportunity for public relations. Poor accessibility can attract negative attention and litigation, but strong accessibility practice can be a genuine differentiator — demonstrating commitment to inclusion in a way that resonates with customers, employees, and the public.

When an organisation buys products or commissions services, accessibility must be a stated requirement in the contract. Verifying vendor accessibility claims — rather than accepting them at face value — is a core part of responsible procurement.

⚠️ Public sector procurement is a particularly powerful tool because of its scale. When government agencies require accessibility across large contracts, the effect ripples through supply chains and can raise baseline accessibility across entire markets, not just within the public sector.