Four different Google map types are available: map, hybrid, satellite, and terrain.
Map specifies Google's map view, with streets labeled.
Satellite shows a color aerial view of the earth, with no labeling.
Hybrid is a cross between map and satellite, showing an aerial photo of the earth, but with important features such as streets labeled.
Terrain displays labeled features such as roads, but on a shaded overlay that gives a sense of topography.