How does Bluetooth connect two devices?

We barely think about it anymore. Earbuds connect to a phone, a keyboard connects to a laptop, a speaker connects to a tablet, all with no wires in sight. None of these connections use the internet. The two devices are simply talking to each other on their own, over a very short distance, with a small radio inside each one. That short-range radio is what Bluetooth is.

Bluetooth sends information through the air using radio waves, much like Wi-Fi does. It uses a band of frequencies around 2.4 gigahertz, a range that has been set aside for short-range wireless devices around the world. The radios inside Bluetooth devices are deliberately weak, which keeps power use low and limits the signal to a small area around you. For most everyday devices, that range is roughly up to about ten meters — enough to leave your phone on a desk and walk a few steps away with your headphones still playing.

Before two Bluetooth devices can really work together, they have to be paired. Pairing is the moment when they exchange identifying information and agree that they are allowed to talk in the future. You usually do this once: hold a button on the headphones, tap them on your phone screen, and from then on the two devices recognize each other and can reconnect on their own when both are switched on. Pairing is what stops your earbuds from happily connecting to a stranger's phone on a bus.

Bluetooth was designed with a very different goal from Wi-Fi. Wi-Fi is built to push large amounts of data over a wider area to connect devices to the internet. Bluetooth is built for short distances and low power, so a small battery in a pair of earbuds can keep talking to a phone for hours. That trade-off is why it has become the standard for personal accessories: wireless audio, keyboards and mice, fitness bands, game controllers, and small file transfers between devices that happen to be near each other.

This article was written using information from Wikipedia.