Love it or hate it, Bluetooth is in almost every gadget we own and use. It's one of the most universal means of communication between devices and thanks to the Low Energy protocol of Bluetooth 4.0 (and 4.1 and 4.2 subsequently), it has been propagating to various accessories, gadgets, wearables, and Internet of Things devices. Right now, I can count 13 things within 2 feet of me that use Bluetooth, and they're not all phones: I also have a speaker, a wireless trackpad, 2 smartwatches, a Fitbit, and so on.

But Bluetooth is slated for even more expansion as beacons start showing up everywhere, multiple items around you and even on you get smart, and your house/office appliances and various things start learning to communicate wirelessly.