A .gif image format is a collection of frames played in a loop that has multiple proprieties.
Here is a .gif image I made in a quick couple of seconds. Every 500 millaseconds the .gif image changes to the next frame in the loop.

Each frame is an individual image itself




If you want to use a .gif format as an avatar, the image's dimensions cannot be above 75x 75y.
By an image standard, that would be this big

If you want a site that turns standard image formats (.png, .jpg, .bmp) into a .gif format, I mainly
use this site.