What are vector images?

From The Book, "Macromedia FLASH 5 Using Flash"
published by Macromedia, Inc. 2000

About vector and bitmap graphics

Computers display graphics in either vector or bitmap format.

Vector Graphics

Vector graphics describe images using lines and curves, called vectors, that also include color and position properties. For example, the image of a leaf is described by points through which lines pass, creating the shape of the leaf's outline. The color of the leaf is determined by the color of the outline and the color of the area enclosed by the outline.

When you edit a vector graphic, you modify the properties of the lines and curves that describe its shape. You can move, resize, reshape, and change the color of a vector graphic without changing the quality of its appearance. Vector graphics are resolution-independant, meaning they can be displayed on output devices of varying resolutions without losing any quality.