Vector graphics (also called graphical modeling, or object-oriented graphics) is a type of computer graphics. Vector graphics uses geometrical objects, like points, lines, curves, and polygons to model the image. Mathematics can be used to describe the graphics. Most often vectors and matrices are used. The other way to model computer graphics is to use raster graphics. They model images as a collection of pixels.
Unlike raster images, vector-based images can be scaled indefinitely without loss of quality. Vector graphics are most often used for diagrams, and other things that can be described using simple shapes. Photographs are most often raster images.