In terms of web components, accessibility means that the web sites and applications provide full control over their features by enabling users with disabilities to access them through assistive technologies such as screen readers.
Assistive technologies work well for the most basic and text-driven web sites and applications. However, the Web is dynamically changing and is now well beyond the realm of text-based experiences. As a result, assistive technologies struggle to keep up.
Web developers can do a lot to bridge this gap between the current challenges which web applications pose to disabled users and the capabilities which assistive technologies support. By providing features, such as full keyboard support, high-contrast visual elements, and text-based equivalents of non-text elements, and by adhering to standards like WAI-ARIA, WCAG 2.0, and Section 508, developers deliver completely accessible and rich Internet applications.