Since the release of iOS 5 (Q4 2011), Windows Phone 8.1 (Q3 2014), BlackBerry 10 (Q1 2013), and Android Jelly Bean (4.3 - Q3 2012), mobile phone operating systems have supported a further subset of Bluetooth protocols known as Bluetooth Low Energy ("Bluetooth LE").
As the name suggests, the Bluetooth LE protocol is a far lower-power type of Bluetooth connection than Bluetooth Classic, making it ideal for low-power devices, or where only small amounts of data need to be transferred. Unlike Bluetooth Classic, which is designed for sustained data transfer, Bluetooth LE "sleeps" between connections.