Bluetooth
Bluetooth is a protocol for wireless communication over short distances. It was developed in the 1990s, to reduce the number of cables.  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. Bluetooth is usually only used for relatively short distances, like a few metres. Some signals can be up to 100 metres.