Bluetooth is a protocol for wireless communication. Devices such as mobile phones, laptops, PCs, printers, digital cameras and video game consoles can connect to each other, and exchange information. This is done using radio waves. It can be done securely. Originally, Bluetooth was developed to reduce the number of cables needed to connect such devices to a PC. Bluetooth is only used for relatively short distances, like a few metres.
There are different standards. Data rates vary. Currently, they are at 1-3 MBit per second. Typical Bluetooth applications are to connect a headset to a mobile phone, or to connect a computer mouse, keyboard or printer. Bluetooth devices use the ISM Band around 2.4 GHz. This can be used worldwide, without the need to pay license fees, but many other devices, like DECT telephones (wireless phones), smart tags with RFID, baby phones use it too. Bluetooth uses the same bands as some WLANs, but the modulation technique is different. Bluetooth uses Frequency-hopping spread spectrum.