100 Days of A11y

Usability & Accessibility

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In prior posts, I've described accessibility in many way. Accessibility boils down to giving equal services and independent access to people with disabilities. However, if a design process is led with universal design principles in mind, a website's usefulness can go beyond WCAG success criteria and become usable by almost everyone. Usable websites create a design that:

Definitions of usability

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ISO defines usability as the extent to which a product can be used by specified users to achieve specified goals with effectiveness, efficiency, and satisfaction in a specified context of use.

Whitney Quesenbery went further to break this definition down into the "5 E's of Usability":

Steve Krug, author of Don't Make Me Think said that usability is about: "...making something that works well - that is - that a person of average or even below average ability and experience can use it for its intended purpose without getting hopelessly frustrated." Krug also stated: "...a website should be self-evident, obvious, and self-explanatory."

Key components of usability assessment are:


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So, why am I learning about usability while I'm studying accessibility? Well, simply put:

Accessibility increases usability for everyone, and usability increases accessibility for people with disabilities.

The key difference being that usability issues affect every user. As web designers and developers we can run across issues that may render a website or app unusable by everyone, but it shouldn't be reported as an accessibility issue. Accessibility issues affect only people with disabilities, but, once corrected, may improve the usability of the site or app for everyone.

Additional reading

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