GPS

http://www.gpsworld.com/gpsworld
The Global Positioning System (GPS) is a satellite-based navigation system made up of a network of 24 satellites placed into orbit by the U.S. Department of Defense. GPS was originally intended for military applications, but in the 1980s, the government made the system available for civilian use. A GPS satellite weighs approximately 2,000 pounds and is about 17 feet across with the solar panels extended.
GPS satellites circle the earth twice a day in a very precise orbit and transmit signal information to earth. The satellites are powered by solar energy. They have backup batteries onboard to keep them running in the event of a solar eclipse, when there's no solar power. Small rocket boosters on each satellite keep them flying in the correct path.
GPS receivers take the received information and use triangulation to calculate the user's exact location. Essentially, the GPS receiver compares the time a signal was transmitted by a satellite with the time it was received. The time difference tells the GPS receiver how far away the satellite is. Now, with distance measurements from a few more satellites, the receiver can determine the user's position and display it on the unit's electronic map. Once the user's position has been determined, the GPS unit can calculate other information, such as speed, bearing, track, trip distance, distance to destination, sunrise and sunset time and more.
This multifunctional technology allows the organizations to benefit while using it. Especially particular organizations which are providing delivery and transportation. The GPS improves customer service by showing exact locations and routs. It makes easier the process of managing field personnel. It reduces time, spent for searching the location and that is why it increases employee production and saves money. The GPS can work in any weather conditions, anywhere in the world, 24 hours a day. There are no subscription fees or setup charges to use GPS.
Although today's GPS receivers are extremely accurate, there are still few disadvantages in the usage. Certain atmospheric factors and other sources of error can affect the accuracy of GPS receivers. This can happen when the GPS signal is reflected off objects such as tall buildings or large rock surfaces before it reaches the receiver. It increases the travel time of the signal, thereby causing errors. GPS units typically will not work indoors, underwater or underground. Heavy foliage and thick branched trees can attenuate and/or block satellite signals. More importantly GPS requires training and retraining as it changes. I would like to mention that having an understanding of maps is always a good back up.
Summing up, undoubtedly, the GPS is a very effective and easy way to find the location without ever being lost and improve the services.