Bluetooth also known as a Personal Area Network, is a telecommunication standard for short range wireless communication between the cell phone, computer, PDA devices. Most Bluetooth devices operate at 2.45GHz and are "class 2" rated, meaning a wireless range of 30 feet. Data can be exchanged at a rate of 1 megabit per second.
Bluetooth is starting to be incorporated as a feature in new cars for hands-free phone use. 
Bluetooth is named for the 10th century Viking king Harald Bluetooth.