Vector files are produced in a drawing program, such as AutoCAD, and the method in which the data is stored is totally different and more efficient that the raster file.

With a vector file, the data is stored as a mathematical formula and the programme does this by relating all locations to a common origin, say a point in "space". You will probably remember drawing graphs at school these always had a vertical and horizontal axis that started at a common origin, zero.

If we think of a graph with say 1000 units vertically and 1000 units horizontally, the drawing package identifies the start of a line by the number of units up the vertical axis and the number of units along the horizontal axis. For example, a point on the graph three vertical increments high and two horizontal increments, is a point in space relative to the origin of say, 0,3,2. Similarly, other points in space can be defined.

The programme includes a system of identifying lines between points and also circles about a point, etc. In this manner, the whole of a drawing is defined in a mathematical language that is quite compact as for as the volume of data is concerned.

Vector files, are typically produced by drawing programs, e.g. AutoCAD. AutoCAD has file extensions of "dwg" or "dxf", other drawing programs use different file extensions. Due to the many varieties of CAD programs and hence vector files, file interchange programmes are available that will convert one vector format to another.