Alt text is an invisible description of a photo that a screen reader can read aloud with audio to people who are blind or visually impaired. Most social media platforms have the ability to edit a photo and add alt text. A brief description of what the photo contains is all that is needed.This is because search engines, such as Google and Bing, crawl web pages and are unable to understand image files unless an alt tag has been set. Alternate text is therefore vital for search engines to help them better understand a page and provide users with the best possible results when searching online.