Bluetooth is a short-range wireless technology used to create PANs (Personal Area Networks) among your devices, and with other nearby devices.
Bluetooth allows you to leave your phone in your pocket, while talking on your phone with a Bluetooth headset - with no wires. You can also exchange contact or scheduling information with other Bluetooth-enabled phones nearby, or send such information to a nearby Bluetooth-enabled printer.
Another common use is to give your laptop computer or PDA wireless high-speed Internet access via Bluetooth and your phone.
Many newer automobiles also have Bluetooth, which can interface with a phone in a pocket, to allow automatic hands-free phone capability.
More innovative uses include playing a game against someone with a similar phone nearby, or using a special Bluetooth pen to send SMS messages by simply writing them on paper.
Bluetooth functionality is divided into separate types of connections known as "profiles". Each of the various scenarios outlined above involve a different profile. Not all Bluetooth devices support all profiles.
For example, most phones support the Headset (HSP) and Handsfree (HFP) profiles, for connecting the phones to headsets and car kits, respectively. But not all phones support the Object Exchange (OBEX) profiles, which let you transfer files (like photos) (FTP) and/or information (like contacts and events) (OPP) to and from other devices. Another profile supported by only some phones is Dial-Up Networking (DUN), which lets you connect a laptop or PDA to the Internet via the phone. Other optional profiles support connecting to printers (BPP), keyboards (HID), and stereo headphones (A2DP, AVRC).
Most Bluetooth phones are "class 2", which means the Bluetooth feature has a range of up to 30 feet. Class 1 phones (which are rare) can have a range of up to 300 feet.
Bluetooth is named for the 10th century Viking king Harald Bluetooth, who united Norway and Denmark.