Location-based services (LBS) are nally coming out of research labs and getting into the hands of nal users. It is fairly common to see cellular carriers and private companies oering LBS to locate your children, friends, and sites of interest, track assets, enhance the security of key personnel, help people with disabilities use public transportation, guide tourists, and many others. Location-based advertisement is becoming a very big business. Very soon users will be receiving customized advertisements in their cellular phones according to their current location. Military-related LBS systems have also been implemented to provide real-time situational awareness. Soldiers are receiving alert messages with additional information according to their current location. The interesting aspect is that LBS applications are just starting to emerge and the potential for growth the next several year is tremendous.

One common aspect of all these LBS applications is that they are built on top of an infrastructure that includes not only the cellular phone and the application that runs in it but also a communication network, a back end application that runs in a server somewhere, and a series of supporting servers and databases that together provide useful information back to the user. This entire infrastructure on top of which many LBS applications can be eciently supported and run is what we call Location-Based Information Systems (LBIS). LBIS are being developed to target problems in many, if not all, sectors of the economy. In this regard, the timing of this book could not be better.