Definition: Bluetooth is a wireless technology that enables mobile phones, handheld computers, and PCs to communicate with each other regardless of the operating system. Its purpose is to replace the wires that are often required to connect such devices. Bluetooth uses radio technology similar to that of Wi-Fi, but its transmissions are limited to about 30 feet. Bluetooths also use 802.15 networking, also called PAN (personal area network).

Details:
This picture to the left shows the most common bluetooth use: connecting your phone to a wireless earpiece. However, you can also use bluetooth to connect your phone to another phone, computer, etc. as shown in the picture at the bottom. How this works is that one device, such as an earpiece, transmits a low-power wave frequency of about 2.45 GHz. This frequency is then found by the other device, such as the phone, and then the two can become connected. Once connected, the two devices can easily transfer data between one another. Some security issues arise with the use of Bluetooth technology because if you don't hide your device from other Bluetooth devices then someone can find your signal. With this, they can connect to your device and send it viruses or worms, which can potentially destroy your device.















Sources:
http://www.howstuffworks.com
http://www.computerconfluence.com