GPS stands for Global Positioning System. It was created by the U.S. Department of Defense to allow the military to navigate under any conditions, anywhere in the world. GPS systems available to consumers today use the same satellite signals as the military uses. Consumer GPS devices can offer many significant advantages, but there are a few disadvantages of which you should be aware.
Advantage: Ease of Navigation
A GPS device is extremely handy. When you are hiking, you can deviate from a path without worrying about how you will find your way back. When you are driving, GPS-based navigation systems can provide you with turn-by-turn directions, a helpful feature in a strange town.
Advantage: Search Nearby Area
Some GPS systems allow you to search the local area for nearby amenities, such as hotels, restaurants and gas stations. This is extremely helpful in some situations. For example, if you are driving cross-country and realise there is a problem with your car, you can search for nearby auto mechanics and select one that is along your route. Your GPS system will show you exactly how to get there.
Advantage: Water Navigation
GPS devices are perfect for water navigation. Since there are no landmarks in large bodies of water, boaters in the past had to use a compass and a map to determine if they were on the right heading, with somewhat imprecise results. But the advent of GPS systems allowed boaters to figure out their exact position on the map. In situations where underwater hazards are a problem, GPS devices allow boaters to steer around hidden dangers.
Disadvantage: Possible Failures
You need to carry a backup map and directions in case your GPS fails for some reason. For example, if you are driving down a city street, the buildings may block the satellite signal, preventing you from receiving position updates. If you are hiking in the wilderness, your handheld GPS receiver's battery may die, leaving you with no way to navigate. For hiking situations, it's a good idea to bring along a compass as well.
GPS signals are not completely accurate. Obstacles like buildings and trees can deflect the signal, causing your position on the GPS screen to be off by as much as 100 feet. Atmospheric conditions (such as geomagnetic storms caused by solar activity) may also affect GPS accuracy. For highway driving, this can cause you to miss a turn or exit.