Here’s the thing. When you use Google Maps, if you zoom in or out, Google downloads new maps to show you the tiles. These are called raster graphics, which are bitmaps because they correspond bit-for-bit with an image displayed on a screen. If you’ve ever seen a file with a .BMP extension, that’s an example of raster graphics. But Apple uses vector graphics. Unlike raster graphics, vector graphics don’t come in files that correspond bit-by-bit with the same image seen on a screen. Rather, vector graphics are made up of mathematical expressions that tell iOS 6 Maps how to draw the map. And since vector maps allow you to scale by any amount without degrading quality - Winckel