Using short-range radio technology, Bluetooth is a way to connect electronic devices without using cables. It is an inexpensive creature comfort for integrating your cell phone into your car's communications system. It offers hands-free use of your cell phone to make calls, receive calls and browse your phone book.
Ford has probably the best-known, upgraded version with its voice-activated Sync communications system, which is standard in most of its car models. Chrysler has a similar system, Uconnect; it's a $395 option on the Chrysler 300.
Nearly every carmaker offers a Bluetooth option. With more and more states creating laws requiring hands-free cell phone usage in cars, Bluetooth is an obvious solution.