In addition to labels, there is special software available to actively track stolen or lost computers and recover them. Often thieves will be unaware that this software is running, and will be unable to delete or disable it even if they notice it.
The tracking software connects to the software company's server whenever the laptop is connected to the Internet. If the owner reports the laptop stolen, the company activates the software and it begins to continually notify them of its whereabouts. The software "phones home" either through an Internet connection or over a dedicated dial-up server. The company then notifies the police, who can work with the thief's Internet service provider or telephone company to locate him and recover the laptop.
A more advanced system of tracking requires the user to have a special piece of hardware installed in the laptop. This device uses a GPS receiver and cellular connection to locate the laptop and report its location to a central server that then notifies police. The GPS system also works with an active Internet connection, reporting its location over the Internet.