Bluetooth® is a cableless transfer-technique, that is finding use especially with mobile devices.
The newest standard it Version 4.0, which, apart from other things, has Bluetooth® Low Energy and Bluetooth® Smart.
This version of Bluetooth® enables more stable connection and consumes less energy. The communication is more safe and can be held up for longer.
Bluetooth® 4.0 connections are encoded and enable safe transfer of data, without access from outside.
Android 4.3, iOS 5 and newer use Bluetooth® 4.0 as standard.