A screen reader is a piece of assistive technology that is frequently used by person with visual impairments or learning disabilities. It is also helpful for people learning English (or another language) and for the elderly.
Typically, a screen reader will start at the top of a website or document and read any text (including alternate text for images). Some screen readers allow the user to preview information, like the navigation bar or all the headings on a page, and skip the user to the desired section of the page. For this reason, using navigation styles like headings is part of creating accessible documents.
Screen reader users often move through a website or document by using only the keyboard, as this provides precise navigation. Hitting ‘Tab’ advances a user to the next item on a page. This means that designing web pages and documents accessibly ensures that screen reader users can navigate the entire site or document using the keyboard.
Screen readers are a tool for testing accessibility because they confirm the flow of the page. If you’re unsure of the order in which a document will be read, either tab through the page or install a free screen reader, like NVDA.
To see a screen reader in action, watch this video from University of Colorado Boulder’s Office of Information Technology.
For a fully keyboard-accessible alternative to this video, view it in Chrome or on any Android or iOS device. You can also view it in Firefox with the YouTube ALL HTML5 add-on installed, or disable Flash in Internet Explorer.