W3C logoWeb Accessibility Initiative (WAI) logo

WAI: Strategies, guidelines, and resources to make the Web accessible to people with disabilities

This is an outdated draft and should not be referenced or quoted.
The latest version is at: www.w3.org/WAI/intro/usable

[Early Rough Concept Draft] Relationship Between Web Accessibility and Usability

Page Contents


This page explores the relationship between web accessibility and usability in the context of standards, guidelines, and conformance. It highlights the overlapping benefits and addresses some questions about making websites, browsers, assistive technologies, and other web tools accessible and usable by people with disabilities.

Understanding Accessibility and Usability

There is significant overlap between usability and accessibility, and not always a clear distinction between them. Usability is about making products and services easy to use by everyone, while accessibility focuses on designing them so that people with disabilities can use them just as easily.

In most situations there is no need to define and differentiate between usability and accessibility, such as when designing websites, web applications, and tools. In fact, usability approaches are essential for designing accessible products and services, while accessibility improves usability overall.

Scope of Usability

In general, usability focuses on making the user experience satisfying. For instance, that website users can find correct information quickly, fill out forms easily, or carry out other tasks effectively.

[Editor note: add some more background about the scope of usability, possibly by listing some of the key approaches and techniques, and emphasizing that it is not about evaluating at the end.]

Scope of Accessibility

Accessibility focuses on ensuring equivalent access for people with disabilities. That is, making sure that the user experience is just as satisfying and that people with disabilities are not disadvantaged.

Accessibility includes requirements that benefit people with and without disabilities. These are general design improvements but they impact people with disabilities to a larger extent. For instance, people with cognitive disabilities are more likely to benefit from clear and consistent navigation, and people with physical disabilities are not able to use websites without keyboard support.

Accessibility also includes requirements that are specific to people with disabilities. For instance, to ensure access for people using assistive technologies such as screen readers that read aloud web pages, screen magnifiers that enlarge web pages, and specialized keyboards that are used to input text.

[Editor note: consider adding something such as "accessibility is not an option, it is a human right" (and point to the UN Convention), to further stress the significance and importance of accessibility.]

Benefits of Usability for Accessibility

[Editor note: this section could also be an <h4> under Scope of Usability.]

Usability is a broad discipline with established approaches and techniques that are essential for implementing accessibility. For instance, approaches to help define usability goals and requirements for projects can be used to define accessibility goals and requirements, and techniques to validate the usability of early designs and implementations can be used to validate accessibility too. In particular the usability methods and procedures for involving and working with actual users are essential for accessibility.

Benefits of Accessibility for Usability

[Editor note: this section could also be an <h4> under Scope of Accessibility.]

One of the many benefits of accessibility is improvement in general usability. Websites, web applications, and tools that are designed to be accessibility to people with disabilities have better usability for everyone.

Usability testing with participants with disabilities is particularly beneficial because many general usability issues are more apparent to users with disabilities. For instance, large amount of links on a web page are likely to be an issue for people with cognitive, physical, or visual disabilities, as well as for people who are new to the website or are less experienced web users. In other words, general usability issues are often highlighted and easier to identify because participants with disabilities are more sensitive to usability issues.

Usable Web Accessibility

The International Organization for Standardization (ISO) defines usability as the "extent to which a product can be used by specified users to achieve specified goals effectively, efficiently and with satisfaction in a specified context of use" (ISO 9241-11). Using this definition, one could say that for most websites:

Put more simply, usability means designing websites to be effective, efficient, and satisfying for everyone, including for people with disabilities. Usable web accessibility is this combination of usability and accessibility, to ensure that websites, web applications, and tools are usable by people with disabilities.

Technical Standards

Technical standards play a vital role in documenting accessibility requirements for people with disabilities, to help developers in implementing usable web accessibility. Developers can simply refer to existing technical standards rather than to research and re-develop the accessibility requirements each time anew.

The W3C Web Accessibility Initiative (WAI) develops a set of guidelines that are internationally recognized as the standard for web accessibility. These include:

The WAI Guidelines include considerations for people with a broad range of auditory, cognitive, neurological, physical, speech, and visual disabilities, including people with age-related impairments. They also include considerations for different types of websites, browsers, and other web-related technologies and tools.

The WAI Guidelines combine these considerations in unified requirements that address different people and situations. For instance, the requirement of text alternatives allows content to be presented in different ways, including in auditory, tactile, or visual forms. It allows developers to provide graphics and illustrations to help people visualize concepts and information, including people with blindness who cannot see images.

Real People

Usable web accessibility means meeting the needs of real people. It means that people with disabilities can perceive, understand, navigate, and interact with websites, web applications, and tools, and that they can contribute equally and without barriers.

An effective way to meet the needs of real people is to involve users early and throughout the design process. It helps developers to understand essential basics of how people with disabilities use the Web. For instance, observing people with disabilities complete complex tasks on an accessible website and struggle with the same tasks on a similar but inaccessible website helps developers to understand the types of barriers and solutions.

Involving users in evaluating web accessibility also helps validate designs, prototypes, and implementations early and effectively. For instance, involving users helps meeting even basic requirements such as providing text alternatives for images, or organizing documents using meaningful headings.

In particular meeting WCAG 2.0 requires developers to understand the needs of people with disabilities, and to select appropriate techniques available to meet these needs in specific situations. For instance, organizing documents using meaningful headings can be done differently depending on the type of content, its purpose, and the web technologies used to provide the content. WCAG 2 provides different techniques to help meet such requirements. However, developers need to make informed decisions to ensure usable accessibility for real people.

@@in practice

@@usability approaches provide a good tool to assess trade-offs between one design/implementation and another.

@@Diverse Needs for Accessibility

[Editor note: this section has been integrated into the Technical Standards section.]

Sometimes accessibility needs of people with different disabilities seem to be diverging or contradicting. For instance, while people with learning disabilities need graphics and illustrations to help visualize concepts and information, people with blindness cannot see images.

The WAI Guidelines include considerations for people with a broad range of accessibility needs and provide requirements that unify them. For instance, they require text alternatives for images so that they can be presented according to the needs of different people, including auditory, tactile, or visual presentation formats. In other words, developers do not need to research and re-develop web accessibility requirements each time they are working on a web project. Instead, they can refer to the existing technical standards.

@@adaptability is part of accessibility

Sometimes developers want to optimize the design for particular audiences or situations. For instance, to improve the usability of an online learning system for students with hearing disabilities or such. This could mean emphasizing particular requirements that are more relevant to those users or situations, such as using simple language and sign language videos to better accommodate people with hearing disabilities.

Fortunately the Web is highly adaptable and allows the same content to be presented to users in different ways according to their needs and preferences. For instance, websites can provide content in different colors, layouts, or presentation formats to meet the needs of a particular user. In some cases websites could even provide different content that serves the same purpose. For instance, different versions of a course, to help students with different learning styles to complete the same curriculum.

Website that are optimized to better meet the accessibility needs of particular audiences can still meet the technical standards. Even if individual presentations of the content are not accessible to all users, websites as a whole could provide default presentations that meet the technical standards to remain accessible for other users with disabilities.

[Editor note: the flow of this is not right -- maybe split into a section on "optimizations" and another on "multiple versions/presentations of the same content" (aka adaptation)?

Usability Beyond Accessibility

@@optimizing a design to specifically increase the *usability* for people with disabilities

Interdependency of Technologies

@@web developers may need to compensate for lack of accessibility support in browsers, markup languages, etc

Harmonized Technical Standards

@@competing standards rather than building on each-others work, especially in the field of usable web accessibility

@@questions check-list

[Editor note: This section is for internal purposes only and will be removed in more mature stages of the draft.]

Question: Can a website meet accessibility standards and be technically accessible, but not be really usable by people with disabilities?
Answer: implictly answered in Usable Web Accessibility, in particular in section Real People, by eliminating the concept of "technically accessible" -- there is only accessible or not.
Question: Can a website be usable by people with disabilities, but not meet accessibility standards (not be "technically accessible")?
Answer: attempted in @@adaptability is part of accessibility but not really clear. Maybe works better if a section on "optimization" is broken out (see note at the end of the section)
Question: When does such poor usability make a website not practically accessible by people with disabilities (even if "technically accessible")?
Answer: implicitly answered in Scope of Accessibility and Benefits of Accessibility for Usability but maybe needs more emphasis?
Question: How do general usability issues impact people with disabilities more than people without disabilities?
Answer: implicitly answered in Scope of Accessibility and Benefits of Accessibility for Usability -- does this need to be differentiated from the previous question?
Question: Does designing a site for optimum "usable accessibility" compromise usability for people without disabilities?
Answer: a bit already in Usable Web Accessibility, some more about trade-offs should come in the intro-section of @@in practice, some more discussion of this particular question should come in Usability Beyond Accessibility
Question: Do "usable accessibility" requirements conflict for people with different disabilities? (for example, website developer: "some people say my site has too many links/ too much information, but then they don't want me using javascript to create expanding menus for progressive disclosure") ("I used used XYZ fancy feature to put my 100s of links in a nice widget, but then people complained it's not accessible to screen readers. But then I put all the links in nested lists and people complained it's too much for people with cognitive disabilities.) Issue: The problem is not inherently accessibility, here, it's usability - you have too many links not well organized.
Answer: implicitly answered in Benefits of Accessibility for Usability -- dies this need more clarification?
Question: What aspects of website accessibility and usability are web developers responsible for, versus browsers and assistive technologies. (for example, website developer: "If the browsers and AT don't do their job well, I shouldn't have to compensate for it, should I?") (for example: should websites have a text resize widget?)
[I think when we talk about accessibility/usability then we also need to briefly mention the context such as browsers and Web technologies. For instance, that HTML does not (yet) provide sections markup, so that the header elements have to be (mis-)used for that purpose. That is getting technical but messaging that "designers may need to compensate for the lack of usability in the browsers and technologies" is important.]
[@@it is about browsers not being usable and therefore website developers sometimes need to compensate for it. This is quite apparent for older people and others who are new to computer but not really an accessibility issue per se. If you are writing guidelines for developers making websites accessible, should they include compensations for browser and AT inadequancy?]
[Another complication when defining accessibility standards and guidelines is the responsibilities of the browsers and other components of web accessbility.]
Answer: should be addressed in Interdependency of Technologies
Question: What if a feature that will improve usability for some users cannot be made accessible (e.g., an Ajax widget)?
Answer: not addressed -- wondering about adding something along the lines of "accessibility is not option, it is a human right" (and point to the UN Convention) in Scope of Accessibility

References and Resources

[X] ISO 9241-11: Ergonomic Requirements for Office Work with Visual Display Terminals, Part 11: Guidance on Usability

[X] Introduction to Web Accessibility

[X] Understanding Web Accessibility

[X] "Distinguishing Between Accessibility and Usability Issues"

Resources for More Information

[maybe list some, e.g., those in the Analysis page list, "yes, list them, this shows the history of the issue and gives it credibility"+1+1]

[x] FOCUS Project [Editor note: moved to "additional resources" because it is still very drafty]