A Bluetooth receiver is a piece of machinery designed specifically for picking up a 2.4 GHz signal from compatible Bluetooth devices. Bluetooth is a proprietary wireless standard that is, as of 2015, often used by computers and other consumer electronics for short-range communication without an Internet connection.
Bluetooth receivers can be built into devices, such as phones or laptops, or installed as separate pieces that provide additional functionality to an existing device. For example, Bluetooth music receivers can be installed on home audio equipment to provide wireless audio controls and stream music throughout an entire house. External Bluetooth receivers often come in the form of small USB adapters called dongles.