Advertisers can sell to you on the street, over your phone and in your car, but there's no way they could actually track you down and pester you in private, right? Think again.
Companies looking to sell you things are currently prohibited from accessing and tracking your location online using standard methods to any distance smaller than 35 kilometers. This means you could easily be a half a city away from where advertisers are trying to target content and never notice they were even there - a situation most of us are perfectly happy with.
Of course, modern technology always provides a way around such things, and Yong Wang and his team at the University of China have discovered a legal way for companies to track you to within a few hundred meters.
It starts with the current method of location used by advertisers - pinging IP addresses. When you visit a site at your home computer or mobile phone, companies can ping your IP address and measure the time it takes a packet of information to return. Knowing the speed at which data travels and the time it took gives companies your rough location - typically within a 200km.
Wang and his team realized that they had other tools at their disposal, such as the seemingly insidious Google Maps. Many large centers, office towers and Universities have physical servers of their own, servers that have their own unique IP address. By pinging all of the servers in a given area, Wang was able to create a comparison to the first stage of pinging and narrow down a far more accurate location. Next, another round of closer-in pinging takes place to even more precisely pinpoint a location.
As it turns out, if you're living and working in a large urban center, legally tracking you to within a few hundred meters proves to be no problem. Using a proxy server can avoid your location from being determined, but Wang's system can be set up to detect when a proxy server is being used.
While rules are still in place to protect our private information, public Internet access and use means that many things we believed were impossible or off-limits are now fair game, so don't be surprised if the advertising outside your downtown apartment window suddenly turns disturbingly specific.