GPS began its life as a strictly military technology but it has now flooded into the everyday lives of billions of people around the world and it's no longer the only constellation providing location services.

Russia has the Glonass system, which originates from the Soviet Union era when they began to devise the system in the 1970s. The European Union has the Galileo system and China has Beidou

Collectively, these navigation satellite constellations are called Global Navigation Satellite Systems (GNSS).

The origins of GPS technology date back to World War II, when the U.S. and British navies deployed navigation systems that used ground-based radio signals. But the idea really got off the ground when the Soviet Union launched Sputnik — the world's first artificial satellite — in 1957.

Just days after Sputnik's launch, American scientists noticed that they could pinpoint the satellite's location based on the Doppler shift of its radio signals — a measure of how the wavelengths seemed to stretch out or contract depending on the satellite's movements.

This got the researchers thinking about creating a space-based navigation system. In the late 1950s, they began developing and testing satellite navigation technology, and the U.S. Navy deployed the operational Transit satellite system in the 1960s.

Then, in 1973, a group of Pentagon officials decided to create a "defense navigation satellite system," laying the groundwork for a system called Navstar-GPS — what we now know simply as GPS. We interview one of the pioneers of GPS, U.S. Air Force Colonel Bradford Parkinson at the end of this article. v

GPS relies on very accurate atomic clocks carried on the satellites. Each satellite emits signals that enable receivers to determine their location and time, according to the FAA.

The receiver on Earth computes the time difference between the time of signal reception and the time it was sent by the satellite to compute the distance between the receiver and the satellite. The receiver needs signals from at least four satellites to be able to compute an accurate position.

These days, many people take Global Positioning System devices for granted. Most people are familiar with the concept of using a GPS system (either as a stand-alone device or in a phone) to find one's way around. GPS can also identify a user's location, which is useful for orientation and even for fun activities such as geocaching (finding hidden caches with the use of GPS devices.) But there are other uses as well, besides location and navigation.

GPS can also be used for tracking, such as adding a tag to an animal to see the extent of its territory. The technology also assists with mapping, such as helping to better define the outline of a country. There are likely thousands of applications for GPS systems, ranging from everything to helping hikers navigate in remote areas, to assisting farmers with precisely seeding their fields, to assisting drones with finding their targets.

"The idea of going somewhere without satellite positioning and maps at your fingertips — or snapping photos without geotagging data — can be as alien to people these days as hitching up a wagon for a run to the feed store. It's an anachronism from another era," Digital Trends (opens in new tab) wrote.

The U.S. Air Force sent the first GPS satellite into orbit in 1978, and many other launches followed over the years.

By the early 1990s, the system was functioning, and its capabilities were demonstrated during the first Gulf War. Allied troops relied heavily on GPS to navigate the featureless Arabian desert, Air Force officials have said. By 1995, the 24th GPS satellite was in position, marking the system's arrival at full operational capacity at that time.

GPS satellites send out two signals — one for military use and one for civilian applications. In the early years, the civilian signal was intentionally degraded for national security purposes. But that changed in 2000 when President Bill Clinton ordered the degradation turned off, making civilian GPS much more accurate. The decision has helped GPS become a more reliable tool for private citizens all over the world.

The capabilities of GPS are constantly improving, as the Air Force launches newer, more accurate GPS satellites on a regular basis. The U.S. federal government is committed to providing a minimum of 24 operational GPS satellites in orbit, 95 percent of the time. There are currently more than 30 satellites up, providing some margin for error.

Air Force Colonel, Bradford Parkinson, was the lead architect for the Global Positioning System (GPS) program. In 1973, he convinced the US Air Force of the value of a new satellite-based navigation system. By building satellites and experimenting to improve them, he and his team provided the world with accurate positioning, navigation and timing services.

The first GPS satellite was launched into space just 44 months after the team's program was approved. Parkinson went on to become a Professor at Stanford University in 1984, the same university that he graduated from with a PhD in guidance control navigation. There he continued to explore the multitude of applications his team's satellite service could achieve, including robotic tractors. From the maps on our phones to real-time aircraft positioning for pilots, Parkinson's lead role in this groundbreaking technology has resulted in some declaring him the 'father of GPS'.