Alternative text (alt-text) in websites and documents is an important part of universal design for the web. This article will outline what alt-text is. In addition, the article will explain how to ensure high-quality alt-text in websites and documents.
Alt-text in Websites and Documents
One principle of the Web Content Accessibility Guidelines (WCAG) requires that web content must be perceivable. In other words, people with a variety of disabilities should be able to perceive web content that is presented audibly or visually, including images. Furthermore, WCAG requires websites to be robust, to work with current and future assistive technologies.
People who are blind read websites with screen readers, software programs that read text aloud. Furthermore, people who are blind or deafblind have Braille displays that work with their screen readers to show the text in Braille. However, screen readers cannot interpret images. Therefore, content creators need to include alt-text for any important images in their websites or documents.
Alt-text is a brief textual description of an image. This description does not appear visually in a website or document. However, alt-text does appear for a screen reader. While someone not using a screen reader looks at an image, a screen-reader user hears or feels the alt-text for that image.
Content creators can write alt-text in most programs they use to develop their content. After they have inserted an image, there is usually an option in a menu that allows them to add alt-text to that image. Some programs may limit the letters in a piece of alt-text. Therefore, content creators must be concise when they decide how to describe an image.
Some artificial intelligence (AI) programs can now write auto-generated alt-text. However, this auto-generated alt-text is often not accurate. For example, AI may use an image’s filename as alt-text. As a result, instead of hearing about the image, screen-reader users may here a series of letters and numbers. Alternatively, auto-generated alt-text may describe an image but not be specific enough. For instance, alt-text for a medicine wheel may describe it as only “a wheel”. This alt-text leaves out crucial information about the image’s context and its cultural importance.
Moreover, content creators choose their images carefully, for specific reasons. People reading the website or document need to pay most attention to certain parts of the image. Furthermore, two (2) or more websites may use the same image for different reasons. As a result, it is best practice for content creators to write their own alt-text. Writing alt-text can help content creators think about why they have chosen a certain image, and what parts of the image they want their viewers to pay most attention to.
Similarly, accessibility checkers for many programs can verify whether or not an image has alt-text. However, these checkers cannot assess the quality of alt-text. Only a website or document’s content creator can decide how well a piece of alt-text describes an image.
Our next article will discuss image descriptions, a different way to make pictures perceivable to a variety of visitors.