Although tracking ads follow people as they browse different websites, Drawbridge uses statistics to do the same across devices. It gathers information on which gadgets are being used and what is being done with them to build up "anonymous" profiles of different users.
The statistics generate a probability for which profiled user might be on that smartphone, tablet or laptop. So far, said Drawbridge, it has drawn up profiles connecting 200 million users to the different electronic gadgets and applications they use during the day and in separate locations.
Drawbridge's technology is based around cookies - small text files widely used by websites to identify visitors and tailor what they see. Drawbridge puts cookies on a device when its browser on it is used to visit a particular website. That cookie logs which browser is being used to access which site as well as the time of the visit.
The firm then compares data gathered by many different cookies placed on many different devices and employs information theory to work out activity patterns of particular users.
A technique from information theory known as "triangulation" allows Drawbridge to be confident of spotting people even though it uses no personally identifiable data such as login names or location information. Once people are profiled, adverts can be tailored to their browsing habits and piped to the separate gadgets they use.
Source: BBC News
