What is a gif you say ? well imagine a jpeg as a static image but this time use all those images into a sequence that allows you to create a motion picture which is still in a image format. To make it any simpler its when you put together all the images that you have either digitally or hand drawn that has been put together forming a loop using the frames per second technique. From these drawn (digitally or hand crafted) pictures the normal animation would be 12 frames per second where as film is 24 frames per second. The reason for this is because animation takes a much longer and slower process compared to video making more details towards the piece of work but it benefits the designer and producer to have complete freedom in what they imagine to be displayed to the audience. GIFs create a continuous motion of the beginning image that has no ending with the illusion of creating a non stop animated video.
For example here is a GIF i managed to find that shows how it starts off from 1 place and goes through a sequence ending with the first frame never knowing when the ending is unless there is a frame that stops at a certain point and returns to the original image.