Bluetooth: how wireless connections between devices work

Bluetooth is a short-range wireless standard (usually up to 10-30 metres) in the 2.4 GHz band. It connects a smartphone to earbuds, watches, speakers, keyboards, cars and smart devices.

Bluetooth connects nearby devices

In plain words

Wi-Fi is like a motorway for moving big loads quickly around the house. Bluetooth is like a walkie-talkie between two friends standing close: low power, little energy, but handy for constant "whispering" between your phone and earbuds or watch.

How it works

Devices find each other and pair.
They remember each other and connect automatically from then on.
Data travels in short packets, and the frequency "hops" quickly to avoid interference.
Different "profiles" describe what is sent: music, calls, files, sensor data.
Bluetooth Low Energy (LE) lets watches and trackers run for weeks.

Bluetooth is like a walkie-talkie for short conversations

Where you'll see it

In every smartphone, tablet, laptop, watch, pair of earbuds and car. Specs list the version - "Bluetooth 5.3", "5.4" - plus codecs (AAC, LDAC) and LE Audio. In our watch comparisons, the Connectivity row.

Does it matter when buying

For most people any Bluetooth 5.x is enough. For earbuds, codecs and connection stability matter more; for a watch, power efficiency. Newer versions slightly improve range, stability and power use, but they do not work miracles.

Myths

Myth: Bluetooth 5.4 sounds better than 5.0. Reality: Sound quality depends on codecs and earbuds, not the version number.
Myth: Bluetooth is bad for your health. Reality: Its power is very low and within safety limits.

FAQ

Why does sound in my earbuds lag behind video?

Because of encoding and buffering; gaming modes and newer codecs reduce latency.

How many devices can I connect?

Several at once, depending on the phone; many earbuds can connect to two devices (multipoint).

Should I turn Bluetooth off to save battery?

Modern Bluetooth LE has almost no effect on battery life.