Military and Government
It was the military the initially developed GPS technology, so it makes sense that they have a lot of use for it.
The major use is for worldwide navigation, everything from aircraft carriers to humvees to fighterplanes. Logistics lays down the groundwork for effective warfare, and GPS plays a major role in moving troops around in a coordinated fashion either worldwide or within a city block. Similarly, missiles can more precisely hit their targets (and not the civilians next door) if they are guided by GPS systems. This may even be used to locate lost soldiers behind enemy lines or in the wilderness so they may be more quickly rescued. The military requires precision, and GPS provides it.
The US government also finds use for GPS devices, primarily for its tracking abilities and law enforcement, although these are somewhat controversial. Warrantless GPS tracking of cars is a favorite tactic for pinning down suspects and for keeping track of those out on bail. Tracking convicted criminals upon their release is another popular use, especially for paedophiles. Again, these are all quite controversial and, in the eyes of many, constitute a major violation of both commonsense privacy and of the Constitution. So, these may or may not be around a decade from now; follow the court cases.
Not all government uses are quite so insidious, however. For instance, GPS has proven to be a major aide to firefighters trying to figure out while on the front lines where the fire might spread next and where to try to prevent it.
Commercial and Scientific
There are many commercial uses for GPS as well. Navigation is important for tracking fleets of delivery trucks and rented cars. Airplanes find it rather nice to be able to locate the landing strip in foggy weather, and radar systems are beginning to be replaced by GPS for many individuals.
GPS tours are a growing feature for tourists. As the device, presumably rented, approach a monument, it can display information relevant to that location.
GPS can be a powerful tool for survey, either commercial or scientific in nature. Being able to precisely match where features are relative to each other is especially handy for geology for measuring earthquake movements or for making the next big skyscraper.
Exact atomic synchronization of facilities across the world, another handy trick of GPS, can be absolutely necessary for coordinating, say, management of NASA’s farflung observatories.
Tracking features are useful for mapping out the movements of critters to better understand them, from grizzly bears to raptor birds.
Finally, what is GPS used for when we consider an individual person? The options are, if anything, all the more varied.
Navigation is, as with the others, the single biggest use. No need for foldout maps covering your windshield anymore; a cute little device sitting on your dashboard can give your directions instead and even updated traffic and construction information. Handheld devices have become popular for recreational use in hiking, mountaineering, or even just geocaching.
Objects may be tracked as well. Laptops are popular, in case they get stolen. Cars and cell phones may contain GPS transmitters in order that both they and the individual carrying them may be tracked. Another potential invasion of privacy lies in devices more directly aimed at tracking individuals such as GPS wrist collars or shoes for everything from wandering toddlers to lost Alzheimer’s patients to your favorite pet.
GPS is universal and universally versatile. Chances are, the ways in which GPS can add to our lives are just going to increase as people come up with new uses for this technology. The possibilities are, forgive the cliché, endless.