Most images you see on your
computer are composed of bitmaps. A bitmap is a map of dots, or bits
(hence the name), that looks like a picture as long you are sitting
a reasonable distance away from the screen. Common bitmap filetypes
include BMP (the raw bitmap format), JPEG, GIF, PICT, PCX, and TIFF.
Because bitmap images are made up of a bunch of dots, if you zoom in
on a bitmap, it appears to be very blocky. Vector graphics (created
in programs such as Freehand, Illustrator, or CorelDraw) can scale
larger without getting blocky.