Location based services (LBS) covers a whole range of applications being developed for mobile phones and PDAs which are based on your handheld device being able to identify your physical position, rather like the GPS (global positioning system) which currently offers computer-based maps and directions for drivers.

Applications being developed range from the prosaic to the bizarre. You will be able to ask a website for your nearest restaurant, taxi service or hospital with the touch of a button. The system will automatically plot your position and be able to give you directions or display a map. Games based on your position in the real world are already popular in Sweden - your opponents are nearby and you have to hunt or flee from them in real time, as well as search for 'objects' in particular locations.

Handsets can be tracked via GPS (global positioning system) which is based on a system of orbital satellites. This has limited accuracy however and additional systems are being developed which use a series of base stations (the same ones which relay your voice and data calls) to establish the handset's position using triangulation.

Location based services are likely to find their way onto high spec smartphones initially, such as Orange's SPV, Sony Ericsson's P800 or Sendo's Z100. Later it will trickle down to more affordable handsets and is likely to become a standard feature on all mobiles over the next few years

There are lots of big plans for LBS. You could receive an automatic warning that you're about to enter a high crime area, and be given evasive directions as a result. You could receive ads by passing a particular location, say, a house for sale, if you've requested info on homes in a particular area. Or you may receive local ads as an alternative to paying for LBS.

There are plans for a Java-based system in the UK which will allow drivers stuck in traffic jams to advise others on how to avoid them. In a trial in the US, large stores can track credit card users, and identify duplicate cards if it's physically impossible for someone to have used their card in two places at once. Also in America, networks are already obliged to provide location details of callers to the emergency services under legislation called E911 (Enhanced 911). Similar legislation is being worked on for Europe and is planned to come into effect in mid-2003.

If your mobile can identify your position, it means that someone else can track where you are. That's good if you're lost, or if you want to know where your children are, but there have been calls by civil liberties groups for legislation governing unregulated use of tracking by employers or the police.