Accessibility (often abbreviated a11y) means designing products that can be used by people with disabilities, including visual, auditory, motor, and cognitive impairments. Inclusive design goes further, accounting for diverse users from the start rather than retrofitting accommodations. The Web Content Accessibility Guidelines (WCAG) provide the global standard, organized around four principles: Perceivable (information must be presentable in ways users can perceive), Operable (UI components and navigation must be operable), Understandable (information and operation must be understandable), and Robust (content must work with current and future technologies, including assistive technologies). Conformance is measured at three levels: Level A (minimum), Level AA (the standard target for most sites), and Level AAA (enhanced, not always achievable). Designing against these criteria produces products that work for the broadest possible audience.
Technical accessibility relies on semantic HTML and ARIA (Accessible Rich Internet Applications) attributes. Semantic HTML uses elements according to their meaning, such as header, nav, main, article, and footer, rather than generic divs, giving screen readers and search engines the structural context they need. ARIA fills gaps where semantic HTML is insufficient, offering roles, states, and properties that assistive technologies can interpret. Landmark roles like banner, navigation, main, complementary, and contentinfo let screen reader users jump efficiently between major page regions. ARIA live regions announce dynamic content changes politely or assertively. Forms must associate labels with fields, mark required inputs, link error messages via aria-describedby, and indicate invalid state with aria-invalid. Touch targets should be at least 44x44 pixels on iOS or 48x48 on Android to accommodate users with motor impairments.
Inclusive design recognizes that disability is diverse and situational. Beyond permanent disabilities, users experience temporary impairments (an ear infection affecting hearing) and situational limitations (holding a baby while shopping, limiting one-handed phone use). The curb cut effect demonstrates that features designed for disabled users often help everyone: captions aid deaf users but also help people in noisy environments, while curb cuts serve wheelchair users but also strollers and luggage. Designers should consider color blindness (affecting roughly 8% of men and 0.5% of women), vestibular disorders that require respecting prefers-reduced-motion, dyslexia-friendly typography choices, photophobia, and cognitive accessibility through plain language. Tools like screen readers (NVDA, JAWS, VoiceOver, TalkBack), high contrast mode, and zoom support are essential to test with, and accessibility audits combining automated scanning with manual review remain the gold standard for compliance.