Presence Technology

Presence technology is a type of application that makes it possible to trace and identify a computing device where it might be, as soon as the user connects to the network.
Instant messaging (IM) is a very common example. Both trademarked products, such as Sametime (IBM Lotus Instant Messaging & Web Conferencing), and freely available ones, such as AIM, can be used to add an existence to any application. That ability makes collaboration possible anywhere and anytime users are online. In another example (from many possibilities), a driver with a GPS-enabled device can be tracked and sent messages warning about traffic delays and suggesting different routes.
Presence technology is an important part of third generation (3G) wireless networks, and is being active across a wide variety of communication devices, including cellphones, laptop, computers, PDAs, television sets, and pagers. Privacy issues are usually addressed by allowing a high degree of user-defined control, allowing people to choose situations in which they are obvious.