What is Alt text in seo?

Alt text is the written copy that appears in place of an image on a webpage if the image fails to load on a user’s screen. This text helps screen-reading tools describe images to visually impaired readers and allows search engines to better crawl and rank your website.
Optimizing your website’s image alt text is your ticket to creating a better user experience for your visitors. Image alt text should be specific but also representative of the topic of the webpage it’s supporting. While ALT tags need to be descriptive they also need to be brief. They should not be full sentences or paragraphs. With a limit of about 125 characters an ALT tag should provide enough detail for users and search engines to relate the image to the context of the page.