Global Positioning System (GPS) comprises of three parts:
24 satellites that orbit the Earth
Ground control stations which monitor the satellites
GPS receivers can be attached to persons or animals, or mounted on an object, such as a vehicle.

The satellites are synchronised to emit encoded navigational information (exact positioning and exact time). Any vehicle equipped with a GPS receiver will intercept these transmissions. Using a simple mathematical formula derived from triangulation, the receiver is able to calculate its own longitude, latitude, velocity and even altitude. For companies implementing GPS applications, this information, most often, would be transmitted to a central dispatch or control location.

Originally designated the NAVSTAR (Navigation System with Timing And Ranging) Global Positioning System, GPS was developed by the US Department of Defence to provide all-weather round-the-clock navigation capabilities for military ground, sea, and air forces.

Since its implementation, GPS has also become an integral asset in numerous civilian applications and industries around the globe, including recreational uses (e.g. boating, aircraft, hiking), corporate vehicle fleet tracking, and surveying. GPS employs 24 spacecraft in 20,200 km circular orbits inclined at 55 degrees.

These spacecraft are placed in 6 orbit planes with four operational satellites in each plane. All launches have been successful except for one launch failure in 1981. The full 24-satellite constellation was completed on March 9, 1994. GPS receivers use triangulation of the GPS satellites' navigational signals to determine their location.

The satellites provide two different signals that provide different accuracies. Coarse-acquisition (C/A) code is intended for civilian use, and is deliberately degraded. The accuracy using a typical civilian GPS receiver with C/A code is typically about 100 metres. The military's Precision (P) code is not corrupted, and provides positional accuracy to within approximately 20 metres.

GPS Applications
One of the fast-growing GPS applications is vehicle tracking. GPS-equipped fleet vehicles, public transportation systems, delivery trucks, and courier services use receivers to monitor their locations at all times.

Public safety services, police, fire, and emergency medical services, are using GPS receivers to determine the nearest service vehicle to an emergency, enabling the quickest response in critical situations.

Recently, automobile manufacturers are installing moving-map displays guided by GPS receivers. For example, several Florida rental car companies are demonstrating GPS-equipped vehicles that give directions to drivers on display screens and through synthesised voice instructions.

Triangulation: Collecting of signals from three or more satellites in carefully monitored orbit from which the receiver computes it's own spatial relationship to each satellite to determine it's position.

Automatic Vehicle Location (AVL) is a technologically advanced method of remote vehicle tracking and monitoring using GPS.

Each vehicle is equipped with a module that receives signals from a series of satellites, and calculates it's current geographical location, speed, and heading. This information can be stored for later retrieval or, frequently, transmitted to a central dispatch/control location where it is displayed on a high-resolution geographical map.

Vehicle tracking UK is based on the concept of GPS. Vehicle Tracking UK is used to keep track of the vehicle movements across the world. Vehicle Tracking in UK has become a more crucial due to the large number of vehicle movements across the country. Time factor is also a major factor for Vehicle Tracking UK.

GPS Vehicle Tracking System is a term used in conjuction with the Vehicle Tracking System. GPS Vechicle Tracking System, concept based on GPS is widely been used all over the world. GPS Vechicle Tracking System covers the lorries, motor cycles, bikes and any objects

             The most well-known global satellite navigation system today is the GPS ("Global Positioning System"). Its roots go back to the early 1960s, when the US Navy set up Transit, which was a satellite navigation system considerably less accurate than GPS, with nominal accuracies of the order of 100-200m. Transit navigation services ended on December 31, 1996. In the summer of 1973, the Defence Navigation Satellite System emerged as a plan to satisfy the needs of all US Services. This was merged with the Navy's Timation navigation system to become Navstar (Navigation Satellite Timing And Ranging), which became more commonly known as GPS.

            "By the turn of the century, a single system - Navstar - may serve most of the United States' global navigation and position-determination needs. Although, right now, it's a military system, the Navstar Global Positioning System (GPS) has shown its worth in a variety of civilian uses: maritime, aviation, and space. If Navstar is eventually adopted for U.S. civilian use, it will provide for the first time a common system for all classes of users, and it may reverse the proliferation of special-purpose navigation and positioning systems"

          The user equipment also needs to measure the timing for signals received from each satellite. Given the time delay between each satellite, whose position is known, then the user equipment can calculate the user's position on the ground.
           Nowadays, all the reception of GPS signals and calculation of positions is usually performed by a self-contained receiver module which is incorporated into the user equipment.