Read the full article on the big hack website: https://bighack.org/how-to-write-better-alt-text-descriptions-for-accessibility/
Adding alt-text to images is an important part of web accessibility. It allows people using screen readers to process images on a page. It includes visually impaired and blind users in the conversation.
WebAIM’s analysis of the top homepages in the world continues to cite missing alt-text as one of the most common accessibility failings. So why, given its importance, is alt-text often so badly implemented?
From a technical perspective, alt-text is simple to add for anyone familiar with a content management system. But knowing how to write a description that is actually useful can be a little harder.
This guidance is aimed at content editors, authors and managers but will be useful to anyone who publishes to social media. Twitter, Facebook and Instagram users can now add alt-text to posts to improve accessibility.
Why alt-text is important for accessibility
Not everyone visiting your website will be able to see the images. Certain disabled, visually impaired and blind users may rely on assistive technology like screen readers or text-to-speech software to process web pages for them.
If no alt-text is provided, a screen reader will simply say “Image” or, depending on the device may read the file name (for example “078GUU.jpeg”) aloud.
Any image that contains critical information or information that improves understanding in the context of the document must have alt-text. If not, that information becomes inaccessible to those users.