Two types of Image Tag which are used at different places. By using them, we can also get some benefits. So lets i talk about Image ALT or Title tag.
ALT
When you put an image in your post, then the search engine can know what is in the image and whose image is in the image.
Title
When a visitor moves the mouse over the image and hovers, the title name of the image will appear.
So just this is the use of ALT and Title of Image Tag