Alt text is also known as "alt attributes" or "alt tags” are used within an HTML code to describe an image on a webpage. It's one of the important SEO factors to boost your search engines rankings. So, here are some best alt text practices to follow.

1) Describe the image specifically
2) Keep it short (fewer than 125 characters)
3) Use your keywords in the alt text
4) Avoid keyword stuffing
5) Don't use your images as text
6) Don't add "image of," "picture of," etc. in the alt text
7) Don’t forget longdesc=""