Glossary
Key terms around WCAG and digital accessibility, sorted alphabetically.
- Accessible name
- The text a screen reader announces for an interactive element (link, button, form field). It is computed from visible text, alt attributes, aria-label, or associated labels. Without it, the element is a mystery to screen reader users.
- Alt text
- A short text description of an image, stored in the alt attribute. Screen readers read it aloud, and it replaces the image if it fails to load. Purely decorative images should get alt="" (empty).
- ARIA
- Accessible Rich Internet Applications — a set of HTML attributes (role, aria-*) that provide extra semantics for assistive technology when native HTML alone isn’t enough. Rule of thumb: prefer native HTML over ARIA whenever it offers the same functionality.
- Assistive technology
- Software or hardware that helps people with disabilities use digital content — for example screen readers, braille displays, voice control, or alternative input devices.
- Conformance levels (A, AA, AAA)
- WCAG defines three conformance levels: A (minimum), AA (the standard most legislation, such as the EAA, requires) and AAA (highest, usually not fully achievable site-wide). This tool checks level AA.
- Contrast ratio
- The brightness ratio between text and background color, expressed as a number (e.g. 4.5:1). WCAG AA requires at least 4.5:1 for normal text and 3:1 for large text, so people with visual impairments can read the content.
- EAA / BFSG
- The European Accessibility Act (EAA) is an EU directive on the accessibility of certain products and services, implemented in Germany via the Barrierefreiheitsstärkungsgesetz (BFSG). Since 28 June 2025 it applies to many digital offerings such as online shops and banking services, and generally requires WCAG 2.1 AA conformance.
- Heading structure
- The hierarchical outline of a page via h1–h6. A correct, unbroken order (h1 → h2 → h3, no skipped levels) lets screen reader users quickly orient themselves via a table-of-contents-style overview.
- Landmark
- A semantic region of a page such as main, nav, header, or footer (or the corresponding ARIA role). Landmarks let screen reader users jump directly between page regions instead of clicking through linearly.
- POUR principles
- The four foundational principles behind WCAG: Perceivable, Operable, Understandable, and Robust. Every WCAG success criterion maps to one of these four.
- Screen reader
- Software that reads screen content aloud or outputs it as braille. Screen readers rely on correct semantics (headings, landmarks, alt text, accessible names) to present content in a meaningful way.
- Semantic HTML
- Using HTML elements for their meaning rather than just their appearance — e.g. a <button> instead of a clickable <div>. Semantic HTML gives assistive technology the right role, state, and behavior for free.
- Skip link
- A usually hidden link at the very top of the page that becomes visible on focus and jumps straight to the main content. It saves keyboard and screen reader users from tabbing through the navigation on every single page.
- Touch target size
- The minimum size and spacing of interactive elements on touch devices (WCAG 2.5.8 recommends at least 24×24 CSS pixels). Targets that are too small or too close together are hard to tap precisely, especially for people with motor impairments.
- Visible focus
- A clear visual indicator of which element currently has keyboard focus (usually an outline or ring). Without visible focus, keyboard users lose track of where they are on the page.
- WCAG
- The Web Content Accessibility Guidelines are the international standard for accessible web content, published by the World Wide Web Consortium (W3C). This tool checks against WCAG 2.1 at conformance level AA.