Before you can start creating maps, you need map data for the location you want to see. This data consists of two files, a shapefile (.shp) and a database file (.dbf). The pair of files should have the same name, for example Singapore.shp and Singapore.dbf. The shapefile format was defined by ESRI.

The shapefile holds both the shapes and coordinates of the map, whereas the database file holds the meaning of those shapes and points. Both are essential for rendering the map. As the file format for shapefiles has been published, and is a de-facto standard, you can create your own shapefiles if you can't find one that exactly matches your requirements.