It is used by most professional designers and is available for the Mac and Windows. See Adobe's site for information about the latest release. The other graphic type that computers can display is the vector graphic. Drawing programs such as Adobe Illustrator and Corel Draw use this. Its images are backed by mathematical formulae which allow them to be enlarged or shrunk without losing their proportions.
Bitmaps have to subtract or add something since they are just groups of pixels to form the page.