What information should be in an alt tag?
The alt tag stands for ‘Alternative tag’ and is there to help Google understand the image and to describe what it is to the Google images search results. The other reason is to tell the browsers what text to display if the image doesn’t load. It simply explains the image, describing what’s in the image. Although this can help your SEO, avoid the temptation to cram in loads of keywords. Keep it natural.