Definition:
GPS - GPS stands for Global Positioning System, a technology that uses satellites to precisely pinpoint the location of a GPS-equipped device. While there are a number of varieties of GPS technology, most iPhone models use what's called Assisted GPS (A-GPS).
Assisted GPS combines standard GPS technology with information derived from cellular data networks the device is connected to for faster and more accurate GPS readings.
Early iPhone models, as well as all iPod touch models, use a triangulation system for determining location, rather than true GPS.
iPhone Models Using A-GPS
iPhone 3G
iPhone 3GS
iPhone 4
Types of Apps That Use A-GPS
Maps
Photos
Third-party apps such as those used for shopping, finding movie times, and exercising
