Internet probe can track you down to within 690 metres

Online adverts could soon start stalking you. A new way of working out where you are by looking at your internet connection could pin down your current location to within a few hundred metres.

Similar techniques are already in use, but they are much less accurate. Every computer connected to the web has an internet protocol (IP) address, but there is no simple way to map this to a physical location. The current best system can be out by as much as 35 kilometres.

Now, Yong Wang, a computer scientist at the University of Electronic Science and Technology of China in Chengdu, and colleagues at Northwestern University in Evanston, Illinois, have used businesses and universities as landmarks to achieve much higher accuracy.

These organisations often host their websites on servers kept on their premises, meaning the servers' IP addresses are tied to their physical location. Wang's team used Google Maps to find both the web and physical addresses of such organisations, providing them with around 76,000 landmarks. By comparison, most other geolocation methods only use a few hundred landmarks specifically set up for the purpose.