Bluetooth

Bluetooth is a short-range wireless technology for connecting personal devices to each other over a few meters — your earbuds, a keyboard, a fitness band, a car stereo. If Wi-Fi is the building-wide network you join, Bluetooth is more like a private cable replacement: a small, low-power link between two gadgets standing right next to you. The quirky name comes from a 10th-century Scandinavian king (Harald Bluetooth) who united warring tribes, chosen as a metaphor for uniting different devices.

Technically, Bluetooth operates in the same 2.4 GHz band as Wi-Fi but is designed for short reach and very low power rather than high throughput. Devices form a tiny network (historically called a piconet) in which one device coordinates the others, and they hop rapidly across many frequency channels to dodge interference. A pivotal split is Bluetooth Low Energy (BLE): a separate, leaner profile built for sensors and wearables that wake up, send a trickle of data, and sleep, letting a coin-cell battery last months or years. Classic Bluetooth, by contrast, is tuned for streams like audio.

Why it matters: Bluetooth and BLE underpin a huge swath of everyday and Internet-of-Things gadgets, precisely because they are cheap and sip power. Set expectations honestly, though: Bluetooth is not a competitor to Wi-Fi or cellular for reaching the Internet — its range is short and its data rates modest by design. It pairs devices in a personal-area network and usually relies on a phone or hub to bridge anything onward. And like all open-air radio, it needs its own security (pairing, encryption); convenience features have repeatedly exposed vulnerabilities, so it is not automatically safe just because the link is short.