Bitmap

Most pictures you see on your computer, including the ones found on the Internet, are composed of bitmaps. A bitmap is a really just a map of dots (or bits, hence the name) that looks like a picture as long as you're not like 2 inches from the screen. Common bitmap filetypes include BMP, 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 gets all blocky. Vector graphics (created in programs such as Freehand, Illustrator, or CorelDraw) scale up much better without getting blocky.