The Vector Data Model of GIS is based on vectors (as opposed to space occupancy raster structures). Its fundamental primitive is a point. Objects are created by connecting points with straight lines. Some systems allow points to be connected using arcs of circles. Areas are defined by sets of lines. The term polygon is synonymous with area in vector databases because of the use of straight line connections between points. Very large vector databases have been built for different purposes. Vector tends to dominate in transportation, utility, marketing applications.
Missouri Spatial Data Information Service