An introduction to the different format types of maps to be used within a geographical information system (GIS) available from Ordnance Survey. The best way to understand raster data is to think of it as a picture or digital photograph that is made up of pixels. As you zoom into a raster image, the pixels get bigger, more blurred and less usable. For vector data, the best way to understand is to think of it as an architect’s drawing or house plan that has been created in a software package. It is made up of points, lines, polygons and text which can be moved or edited. When you zoom in to a vector image, it will still be usable. There is very little you can do to change raster files, unless you have a photo editing package. All you can really do with the image is to make it grey scale, add a tint or make it a negative. You cannot remove features from the map or edit them. Raster mapping is a good backdrop map to add your own information. Vector data can be seen as more intelligent. The point, lines, polygons and text all have attributes that means you can for example select all of the buildings and turn them blue. You can also switch off features if your map is looking cluttered. The attributes can also be used to link your own information to make your map more informative. Source.