GPS navigation technology is hitting the mainstream, but what do you look for in a gadget that tells you where to go, asks Alex Kidman.

Have you ever been lost while driving? Short of crashing into things, it’s just about the worst thing that can happen to you while on the road, especially if you’ve got kids in the back. Maps might give you the lay of the land, but unless you can work out where you are on them – and get them the right way up – they’re just big origami obstructions to the driver’s view.

This is where GPS devices come in. GPS stands for Global Positioning System, developed in the first instance by the US military so that they might have a hope of working out where their missiles and soldiers allegedly were, but opened up for proper public use back in 2000. By 2010, it’ll be joined by a European-backed set of GPS satellites known as Galileo, which should improve accuracy in certain latitudes, as well as ensure signal authenticity outside of times of war. GPS tracks your movement based on the positions of dozens of satellites orbiting the planet. Once you’ve got a fix, you can work out where you are to within a few metres, and if you combine that with mapping software that can turn the longitude and latitude coordinates that GPS units work with into street locations, you can plan routes and keep track of where you are on the road at any given moment – and with no folding paper in sight. Those are the basics of how each and every GPS navigation unit works, but what should you look for when buying a GPS?