AltAttribut

The AltAttribut, commonly referred to as the alt attribute, is an HTML attribute applied to image elements (img) to provide a text alternative for the image. It supports accessibility by conveying the image content to users who rely on assistive technologies, and it also helps search engines understand the page content.

Usage is straightforward. In HTML, an image includes the alt attribute as: <img src="path.jpg" alt="Description of the image">. If the image is purely decorative and conveys no information, the attribute should be present but empty: alt="". For images that double as controls or links, the alt text should describe the function, such as alt="Home" for a logo that links to the homepage.

The content of the alt text should describe the image’s meaning or function rather than its appearance or filename. For complex graphics or diagrams, a concise description is helpful, with a longer explanation provided elsewhere on the page or via a figure caption or accessible description.

Best practices include keeping alt text concise, ideally under 125 characters, and avoiding phrases like "image of" or "picture of." The description should be accurate and not misleading. Decorative images should not add information through alt text that is not present visually.

In addition to img, the AltAttribut can appear on other elements such as area in image maps. While it complements a title attribute, it should not replace accessibility requirements, and the title attribute should not be relied upon for screen readers.