"Bluetooth" technology, first developed in 1994, got its name from a 10th century Danish king named Harald Bluetooth, who was said to unite disparate, warring regional factions -- much like Bluetooth is intended to provide a common communication medium for technologies in different industries (e.g., computers, mobile phones, and automotive devices).
Operating in the same 2.4GHz spectrum as other wireless technologies, like some wi-fi 802.11 protocols, Bluetooth was intended as a wireless replacement for cables. With Bluetooth, you can send a page to print, for example, to a printer downstairs instead of having to connect your computer and printer with an unsightly USB cable. Bluetooth creates a 10-meter (33-foot) radius wireless network, called a Personal Area Network (PAN) or piconet, which can network between 2 and 8 devices.
Bluetooth range and transmission speeds are typically less than Wi-Fi (a.k.a., wireless LAN) capabilities. Bluetooth v3.0 + HS -- "Bluetooth high speed technology" -- devices can deliver up to 24 Mbps of data (faster than wireless-b, though slower than wireless-a or wireless-g). Despite these drawbacks, Bluetooth uses less power and costs less to implement than Wi-Fi and is generally considered a more secure wireless technology that's less prone to interference.
The Bluetooth 4.0 specification was officially adopted on July 6, 2010. Bluetooth version 4.0 features include: low energy consumption, low cost, multi-vendor interoperability, and enhanced range. The hallmark feature enhancement to the Bluetooth 4.0 spec is its low power requirements -- devices using Bluetooth v4.0 are optimized for low battery operation and can run off of small coin-cell batteries, opening up new opportunities for wireless technology. (Instead of fearing that leaving Bluetooth on will drain your cell phone's battery, for example, you can leave a Bluetooth v4.0 mobile phone connected all the time to your other Bluetooth accessories. In fact, you may be able to go years without charging your mobile device.)
Bluetooth Uses and Devices
Bluetooth, because it can simultaneously transmit both voice and data, has been widely adopted as the technology of choice for devices like hands-free headsets and auto in-dash GPS systems, which can communicate with a cell phone for hands-free calling and downloading real-time mapping data.