# Accessibility (a11y) Accessibility (abbreviated "a11y"; 11 letters between 'a' and 'y') is the practice of designing products, services, and environments usable by people with disabilities. In digital contexts, it means ensuring websites, apps, and software work for users with visual, auditory, motor, or cognitive impairments. Good accessibility benefits everyone; curb cuts help wheelchair users and parents with strollers alike. Web accessibility is guided by the Web Content Accessibility Guidelines (WCAG), developed by the W3C's Web Accessibility Initiative (WAI). Legal requirements like the ADA (US), EN 301 549 (EU), and Section 508 mandate accessibility for many organizations. Beyond compliance, accessible design often improves [[Usability]] and [[User Experience (UX)]] for all users. ## WCAG Principles (POUR) | Principle | Description | |-----------|-------------| | **Perceivable** | Information must be presentable in ways users can perceive | | **Operable** | Interface components must be operable by all users | | **Understandable** | Information and operation must be understandable | | **Robust** | Content must work with current and future technologies | ## Common Accessibility Requirements - **Alt text**: Descriptive text for images - **Keyboard navigation**: All functionality via keyboard - **Color contrast**: Sufficient contrast ratios (4.5:1 minimum) - **Focus indicators**: Visible focus states - **Semantic HTML**: Proper heading hierarchy, landmarks - **ARIA labels**: Accessible names for interactive elements - **Captions/transcripts**: For audio and video content - **Resizable text**: Support for text scaling ## WCAG Conformance Levels | Level | Description | |-------|-------------| | A | Minimum accessibility | | AA | Standard target (most legal requirements) | | AAA | Enhanced accessibility | ## Assistive Technologies - **Screen readers**: JAWS, NVDA, VoiceOver - **Screen magnifiers**: ZoomText, Windows Magnifier - **Voice control**: Dragon, Voice Control - **Switch devices**: For users with limited mobility - **Braille displays**: Tactile output ## Testing Tools - **axe**: Browser extension and CLI - **WAVE**: Web accessibility evaluator - **Lighthouse**: Chrome DevTools audit - **Pa11y**: Automated testing tool ## References - https://www.w3.org/WAI/WCAG21/quickref/ - https://webaim.org - https://a11yproject.com ## Related - [[Usability]] - [[User Experience (UX)]] - [[User Interface Design]] - [[Human-Computer Interaction (HCI)]] - [[Design Systems]]