Wi-Fi is Ethernet's wireless cousin: it does the same layer 2 job, but over radio. Devices connect to an access point, which is usually built into your home router. The access point joins the wireless devices to the wired network.
Each Wi-Fi network has a name, its SSID, which the access point announces several times a second so devices can list it. A big building might have many access points with the same SSID, and your phone moves between them as you walk around.
Wi-Fi uses a few radio bands. 2.4 GHz reaches further and goes through walls better, but it's slower and crowded: microwaves, Bluetooth and the neighbours' Wi-Fi all use it. 5 GHz is faster with more room, but has a shorter range. 6 GHz (Wi-Fi 6E and 7) is faster again and quieter, with the shortest range.
Each band is split into channels. Two networks on the same or overlapping channels take turns to talk, which slows both down. In the 2.4 GHz band only channels 1, 6 and 11 don't overlap, which is why routers usually pick one of those.
Radio only carries one sender at a time on a channel, so Wi-Fi devices listen before they talk and wait if someone else is sending. That's one reason Wi-Fi gets slower when lots of devices are busy, and why a cable is still the steadier choice for a games console or a desktop computer.
What is a Wi-Fi network's name called? (four letters)
| Access point | Joins Wi-Fi devices to the wired network. |
|---|---|
| SSID | The network's name. |
| 2.4 GHz | Further reach, slower, crowded. Channels 1, 6, 11. |
| 5 / 6 GHz | Faster, more channels, shorter range. |
| Channel | A slice of a band; shared by everyone on it. |