Global Positioning System - GPS - devices have become everyday items to many of us as their cost has fallen.

Why would you want a system though?

These devices communicate with geo-stationary satellites, which tell the device, exactly where on Earth it is. Very useful.

GPS devices are now so miniaturized that they can be worn on the wrist, like a watch. People convicted of certain crimes may be allowed to serve part of their sentence in the community, rather than a penal institution, on condition that they wear a GPS transmitter permanently strapped to one ankle. The authorities can then track the felon, wherever he or she goes.

GPS navigation systems are commonly fitted in trucks and delivery vans and recreational vehicles so that courier companies can achieve faster deadlines because drivers never get lost.

An increasing number of drivers are specifying a GPS system when ordering a new automobile. The built in software interprets the GPS information into a series of spoken commands, like "Turn Left at the gas station" or "You've missed the turning, take the next right and turn around".

A GPS system means that you can use any roads, stay off the main routes. That you get where you are going, miss the traffic and see some scenery at the same time. You can turn off your planned route if there is an accident ahead that is going to mean long delays, and still know exactly where you are.

GPS systems can be installed in cell phones as well as satellite phones. Sportsmen and women can use GPS devices to calculate how far they have run or paddled, their current speed and average speed.

At sea, where landmarks are few and far between, a GPS system can mean the difference between life and death for sailors and most boats and ships and boats now have one installed.