how does ipad (2) wifi maps work without connection

I haven't used ipad without an internet connection for navigation since I knew it does not have a gps connection. Couple of days ago I had just loaded directions from home to a particular place. Though I did not have any connection after I have left home, it was really accurate in showing me on the map. How is that possible, is it just the combination of accelerometer and compass used by the ipad? I am just curious, I have ios6 installed and I wasn't in a car, I just biked there.