The most common images names that you will see are....
jpeg = [pronounced as jay - peg] Joint Photgraphic Expert Group

Bitmap = In computer graphics, a bitmap or pixmap is a type of memory organization or image file format used to store digital images. The term bitmap comes from the computer programming terminology, meaning just a map of bits. In certain contexts, the term bitmap implies one bit per pixel, while pixmap is used for images with multiple bits per pixel.

PNG = Portable Network Graphics.