One of the attractions of the internet is that it seems to make distance and location irrelevant.

No matter where you are in the physical world as long as you are online you are the same place as everyone else in cyberspace.

But lately that free-floating nature of the net has started to break down.

Sites such as Yahoo, MSN, Google and 192.com have started pushing local search services that link what you are looking for to shops and services near

where you are in the real world.

To do this they try to link the net address, or IP number, of the computer you are using to browse the web to a physical location.

Route march

Sean Phelan, founder and chairman of Multimap, said the reason they are getting interested in location is simple: money.

Getting more information about where someone is helps to target the adverts displayed on the page someone is seeing.

"Every company is spending more every year on internet advertising," said Mr Phelan.

"They are getting better and better at measuring responses and they know what works and what doesn't."

For instance, said Mr Phelan, adverts telling people about the M6 toll road ran alongside searches that people did for the M6 and proved very useful at raising the awareness of the road.

Search sites were also getting more interested in capitalising on the classified adverts that, currently, appear in small circulation local newspapers.

But finding out where someone is based on their IP address is not as straight-forward as it sounds.

Firms such as Quova have sprung up that make a business of working out what where in the world those net addresses actually are.

Data track

Marie Alexander, president of Quova, said several forces were making locating net addresses more urgent.

Stringent compliance regulations increasingly force firms to know who they are trading with. As fraud levels on the net rise, companies want to be sure that customers paying by credit card are where they should be.

A study by credit scoring firm Experian has found evidence of fraud in 68% of orders where the IP address was in a different state from a customer's listed billing address.

Other research found that 64.4% of customer orders routed via satellite were fraudulent and 12.8% of those that passed through international and regional proxies.

Quova's Ms Alexander said that the way the net has grown makes it tricky to work out where net addresses are.

"It's an accumulation of many disparate networks that have been connected together," she said.

The customs that define how net addresses are used in one network may not apply to another, she said.

"In the same way as the rules of the road for London do not work in Paris."

The process of tying net addresses to geolocations starts with the registry of the 1.4 billion assigned IP numbers.

All of these numbers are assigned to someone but simply knowing who that is often gives little clue as where a net address is being used.

For instance, said Ms Alexander, Quova's quota of net addresses are listed as being in its offices in Redwood City. However, they are actually administered out of Quova's building in Mountain View.

Similar problems can occur during takeovers or mergers and information about who owns a block of net addresses takes time to get updated.

Equally many companies that have regional offices around the world use a fixed pool of addresses that are given out as needed. This means a relatively small group of net addresses can serve a much larger population of users.

Local interest

Ms Alexander says that information about net addresses is continually shifting. In any one month up to 7% of the 1.4 billion IP addresses will change location.

To start to get round this confusion Quova traces the route that traffic takes to a particular net user.

"We look to see how long traffic takes between each one of those routes, what's the distance?" said Ms Alexander. "We pull all of that data together, study it and determine how many of them match up and how many point to some same location."

What also helps to pinpoint positions or who owns hardware is the name it is given by net administrators.

Using these different methods helps Quova pin down net addresses down to city level and from there it uses other techniques to get even closer. The ultimate step is to get researchers to ring up and find out where offices or hardware is sitting.

While some might see this ability to locate people as an intrusion Mr Phelan from Multimap's only sees it is a good thing. It was a way, he said, of taking your local links with you.

"When I'm travelling in the US I listen to the BBC Today programme in the morning and have that intensely local experience thanks to the internet," he said.

"Just because I am in America does not mean that I cannot get that local information when I am not at home."