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Accessibility Glossary

Look up the meaning, examples, and limits of terms such as WCAG, ARIA, keyboard accessibility, alt text, and PDF accessibility. For steps you can follow, start with the practical guides.

Need steps to follow? Explore the practical guides

Terms

  • Accessible Authentication

    Accessible authentication reduces the need to memorize, transcribe, or solve puzzles to sign in. Learn the WCAG 2.2 AA/AAA distinction and how to check password managers, pasting, and account recovery.

  • Target Size

    Target size is the area you can activate with a mouse, trackpad or touch screen—not just a mobile concern. Learn the WCAG 2.2 AA/AAA dimensions and exceptions, and how to check the actual hit area.

  • VPAT / ACR

    A VPAT is a template for producing an Accessibility Conformance Report, or ACR. ACRs are often used in procurement and vendor review; they are not the same as user accessibility reports, automatic certification, or whole-product guarantees.

  • WCAG

    WCAG organizes web accessibility needs into testable success criteria. Learn its four principles, cumulative A/AA/AAA levels, the differences between 2.1 and 2.2, and why scans cannot replace a complete evaluation.

  • Web Accessibility

    Web accessibility is the practice of making websites usable by people with different abilities, devices, and situations. Learn how it relates to WCAG, assistive technologies, user experience, and practical product work.

  • ARIA

    ARIA is a set of roles, states, and properties that help assistive technologies understand complex or custom interactive components. Learn when to use ARIA and when native HTML is better.

  • Keyboard Accessibility

    Keyboard accessibility means users can complete core tasks with Tab, Shift + Tab, Enter, Space, and arrow keys without relying on a mouse.

  • Color Contrast

    Color contrast affects whether text, buttons, errors, and UI states are readable. It is one of the most common WCAG AA checks.

  • Focus Indicator

    A focus indicator shows keyboard users where they are. If focus styles are removed or weak, users can get lost.

  • Accessible Name

    An accessible name is the name assistive technologies use to identify buttons, links, form fields, and interactive controls.

  • Screen Reader

    Screen readers present web content, names, roles, and states through speech, braille, or both, and support navigation and interaction. Learn why inspecting the accessibility tree cannot replace real assistive-technology testing.

  • Accessibility Overlay

    An accessibility overlay is an added site-side tool that may offer personalization or runtime patches. Distinguish it from source fixes, assistive technology, and conformance evaluation.

  • Accessibility Statement

    An accessibility statement is a public page that explains a website or digital service’s accessibility status, applied standard, known limitations, improvement work, and feedback channels. It is not a certification or a compliance guarantee, but it helps users understand how barriers can be reported and followed up.

  • Automated vs Manual Accessibility Testing

    Automated accessibility testing can quickly surface some WCAG and best-practice issues, while manual testing is still needed for content meaning, task flow, keyboard use, and assistive technology context.

  • Alt Text

    Alt text communicates necessary information when an image cannot be seen or loaded. Good alt text depends on the image’s purpose in context, not only what appears in the picture.

  • PDF Accessibility

    PDF accessibility concerns whether a document has language, tags, heading structure, bookmarks, links, image alternatives, and form information that assistive technologies can understand.

  • Semantic HTML

    Semantic HTML uses the correct elements for structure and behavior so browsers, assistive technologies, and search engines can understand the page.