Bluetooth is a radio-wave technology, used over short distances, which allows electronic devices to communicate with each other wirelessly.  Bluetooth technology is used in wireless audio such as speakers, receivers and headphones so that you can stream your music wirelessly from your iOS or Android device.  For an easy to understand explanation of what Bluetooth is, how it works, and what it’s used for read this article http://www.explainthatstuff.com/howbluetoothworks.html