Most GPS devices have a memory card slot. This serves several purposes. Firstly, a memory card allows you the ability to add more maps, so if you are going on a driving trip around Europe you can download the maps on to your memory card. The card also allows you to add lots more points of interest, so if you wish to add all the sports stadiums and fast food restaurants you can. Some GPS devices even allow you to download photographs and use them on your maps.