The urbandictionary.com says :
Graphics Interchange Format. GIFs are image files that are compressed to reduce transfer time. The proper pronunciation of the acronym is a soft “g” sound: like JIF.
This above is an animated graphic of the map of the USA throughout their history.
It is too quick, so you can watch each single picture on this website : http://gif-explode.com
Now if you prefer the commented version, you can watch :