Definition: A screen reader is a software application that interprets the content of a screen — text, images (via alt text), interface controls, and navigation elements — and outputs it as synthesised speech or refreshable Braille, allowing users who are blind, have low vision, or have other print disabilities to access and interact with digital content. Screen readers process the accessibility tree of a web page (derived from HTML semantic structure and ARIA attributes) to navigate, read, and interact with content sequentially or by jumping between element types.
Why It Matters: Screen reader compatibility is one of the primary requirements of WCAG and ADA/Section 508 compliance. Approximately 7.5 million people in the United States have visual difficulties that make standard screen viewing difficult or impossible — and screen readers are the primary technology through which many of them access the web. A website that is not navigable by screen reader is effectively inaccessible to this audience. For web designers and developers, understanding how screen readers interpret HTML — and how poor semantic structure, missing alt text, unlabelled form fields, and inaccessible custom components create barriers — is essential knowledge for building accessible websites. Screen reader testing is a required component of a thorough accessibility audit.
How It Works: The most widely used screen readers include JAWS (Job Access With Speech, the dominant professional-grade Windows screen reader), NVDA (NonVisual Desktop Access, a free open-source Windows alternative), VoiceOver (built into macOS, iOS, and iPadOS), TalkBack (built into Android), and Narrator (built into Windows). Screen reader users navigate web pages using keyboard shortcuts — jumping between headings, links, form elements, and landmarks rather than scrolling visually. This is why proper heading hierarchy, meaningful link text (not “click here”), labelled form inputs, and logical tab order are critical accessibility requirements. Web developers test accessibility by navigating their sites with a screen reader to identify barriers that automated tools miss.
Related: WCAG, Accessibility Audit, Keyboard Navigation, ARIA, Alt Text