Developed by Ericsson back before the brand became irrelevant in America, Bluetooth was meant as a way to wirelessly send files between your phone and your computer. Since then it's gone through seven iterations and can now be used to stream music through wireless headphones. You can find it in everything from phones to fridges. And, of course, in the ears of every self-important douche bag able who can afford a wireless earpiece. Thanks, Ericsson!