Global Positioning System
The Global Positioning System, GPS, is a network of satellite in Earth orbit which can be used to triangulate one's position through the use of a GPS receiver.
How the GPS System Works
GPS receivers are an extremely fast and easy way to navigate. With the ability to tell you where you are, where you're heading, how to get there, and where just about anything else is they are tough to beat for convenience. It is easy to come to rely on GPS with all of its features and convenience, but it is important to remember that like any other electronic device it may fail. While the GPS network itself it very robust, requiring little more than regular corrections from ground based stations, GPS receivers are small relatively fragile devices than may break or run out of power.