Provide alternatives for images, video and audio content
Users with visual impairments may not be able to see or interpret visual content, such as images and video. As designers you must provide text that accurately describes the nature of all visual content. Users with hearing or cognitive impairments, and those for whom the language spoken in any video content is not their primary language, may not be able to hear or understand spoken audio in video content.
Image and video content usually requires far higher internet speeds than text, so providing text alternatives also helps users who are looking at your content with a poor internet connection. You must provide a mechanism for designers and content authors to allow them to associate text alternatives with images and videos.