A screen reader is assistive technology that uses speech synthesis to read aloud text and UI elements on a computer screen. It is an essential tool for users with visual impairments to access websites and applications. WHO's published figure as of 2026 puts the number of people worldwide with a near or distance vision impairment at 2.2 billion or more, but this uses a broad definition that includes mild conditions such as presbyopia and does not by itself represent the number of screen reader users. Screen readers are more than simple text-to-speech tools; they analyze page structure and provide keyboard-based navigation between headings, links, forms, and other elements.

Major screen readers include NVDA (free, open-source) and JAWS (commercial) for Windows, VoiceOver (built into the OS) for macOS/iOS, and TalkBack (built into the OS) for Android. These interpret the HTML DOM structure and accessibility tree, incorporating ARIA attribute information to convey content through speech. NVDA is well-suited for developer testing because it is free to use. In WebAIM's tenth Screen Reader User Survey (conducted from December 2023 to January 2024), JAWS at 40.5% and NVDA at 37.7% were nearly even as the primary screen reader, and which product leads varies by region.

Building screen reader-compatible websites requires several key practices. Using semantic HTML allows screen readers to recognize page landmarks (header, nav, main, footer), enabling users to quickly navigate to desired sections. Proper alt text conveys image content, and ARIA labels supplement the roles and states of custom UI components. Correct use of heading hierarchy (h1 through h6) lets users jump to specific locations from a heading list.

Keyboard accessibility is central to screen reader support. Screen reader users do not use a mouse; they navigate with the Tab key and activate elements with Enter. Focus indicators must be visually clear, focus order must be logical, and all interactive elements must be keyboard-operable. Modal dialogs require focus trapping to prevent navigation outside the dialog.

A common misconception is that screen readers are used only by people with visual impairments. In reality, users include those with learning disabilities, temporary visual impairments (such as after eye surgery), and people who want to consume information via audio while multitasking. Another misconception is that heavy use of ARIA attributes ensures compatibility, but the first rule of ARIA is "if you can use a native HTML element, don't use ARIA."

From a character count perspective, screen readers also read non-visible text (alt attributes, aria-labels, visually-hidden text), making character count management of these hidden texts important. The specification sets no upper limit on alt text length, but keeping it to around 125 characters is a practice that comes from avoiding truncation in older screen reader environments, and aria-label values likewise should be kept to a length that can be understood in a single hearing. When assessing the total text volume of a page, both visible and hidden text should be considered.