Bluetooth is typically a low power, medium range device, in fact it can reach up to 10 meters. Bluetooth operates on the same frequencies as WiFi, 2.4Ghz.Connections are normally one to one meaning no group communication is allowed by the protocol. The connection is established by a master device, which connects to a slave device. In internet terminology the master is the client and the slave is the server.
Arduino Bluetooth Tutorial HC-05 – [Link]