Since the development of latitude and longitude, there has arguably been no greater innovation in the field of navigation than the Global Positioning System (GPS). Originally used by the military to track troop movements, GPS is an array of satellites sending signals to receivers on the ground that use the information they receive to calculate their exact position.

Over the past few years, a number of companies have introduced GPS receivers specifically designed with outdoorsfolks in mind. Hikers can use GPS to pinpoint their exact backcountry locations; combine this information with an accurate topo map, and you'll never get lost. You can also program routes directly into your GPS receiver, which will tell you when you've gone off track.

Though there's a bit of technical terminology involved with GPS, learning to use your receiver is simple once you've mastered basic principles of navigation. If you can use a compass, you can use GPS. Let GPS expert and longtime hiker John Milne show you the way with his step-by-step tutorial.

Using GPS Devices - The Series In the Beginning - An introduction to the GPS revolution. Making Sense Out of North - How the difference between magnetic and true north affects navigation. Calculating Global Position - Introducing map datum. Using UTM - Another way to find yourself. Getting There with Goto - Let your receiver steer you right. Staying the Course - Route planning, GPS-style. Get the Track Back - Using your unit to record and share your route.