I was recently a contestant on Jeopardy. What is bluetooth was the question that won me a lot of money. The game show host gives you answers, and you have to provide the correct questions. The answer stated that this is only compatible with certain cellular devices and it allows you to operate your phone hands free. I have a bluetooth compatible cellular phone, and I use my hands-free bluetooth accessories all the time. That is how I knew that what is bluetooth was the question.