On a bitmapped screen every pixel can be manipulated.
Pixels are the dots that make up a visible image on the screen.
Drawing on the Macintosh screen consists of manipulating memory bits that QuickDraw translates into an analogous manipulation of pixels. This allows your application to create shapes and characters in differing sizes and differing styles. Such flexibility gives your application and its users many of the capabilities of a design studio and a print shop. Your application performs all graphics operations in graphics ports. While your application can draw directly into basic and color graphics ports, you can improve your application's appearance and performance by constructing images in offscreen graphics worlds and then copying them to onscreen graphics ports.