“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.” (From Sharpened Glossary)