How does Wi-Fi work? Radio waves and your router

Wi-Fi (often typed wifi) works by turning data into radio waves. Your router and your devices each have a small radio that sends and receives on set frequencies, 2.4, 5 or 6 gigahertz, following shared rules so that phones, laptops and TVs from any maker understand each other. Wi-Fi does only one job, covering the last few meters from the router to the device; the router passes everything on to your internet connection through a modem.

In short

• Wi-Fi is a short-range radio link between devices and a router, not the internet itself.
• Lower bands reach farther and through more walls; higher bands carry more data over shorter distances.
• Devices on one channel take turns, so a crowded network slows everyone on it.

How does Wi-Fi send data through the air?

Wi-Fi is a radio system, like FM radio, only two-way and much faster. A radio wave is a ripple in the electromagnetic field, the same kind of thing as light but with a longer wavelength. A transmitter makes a wave and changes it, shifting its strength and timing in precise patterns; each pattern stands for a group of bits, the 1s and 0s that make up all data. The receiver reads the patterns back. Modern Wi-Fi splits its channel into many narrow subchannels and sends bits on all of them at once, which makes the signal tougher against interference.

The waves are short. At 2.4 GHz, 2.4 billion cycles a second, one wavelength is about 12.5 centimeters; at 5 GHz, about 6 centimeters. That size is why the antennas fit in a phone. It also explains how the bands behave: higher frequencies carry more data but fade faster and pass through walls less well.

Wi-Fi takes turns. On one channel, only one device can transmit at a time, so every radio listens first and waits if it hears someone else, a rule called "listen before talk". Newer versions let a router talk to several devices at once by splitting the channel, but the principle stands: a channel is shared, like one lane of a road.

What's the difference between 2.4, 5 and 6 GHz?

Routers now broadcast on two or three bands at once, and devices pick one.

	2.4 GHz	5 GHz	6 GHz
Reach and walls	Farthest, best through walls	Medium	Shortest, weakest through walls
Speed	Slowest	Fast	Fastest
Room in the band	Little: only 3 channels that don't overlap in the US	Many more channels	The most, with the widest channels
Crowding	Busy: neighbors' networks, Bluetooth, microwave ovens	Less busy	Least busy, newest devices only
Since	The first Wi-Fi, 1997	1999	Wi-Fi 6E, early 2020s

Use the 2.4 GHz band for distance and for smart-home gadgets; use 5 or 6 GHz near the router for speed. Many routers handle the choice automatically, steering each device to the band that suits it.

Why do walls and distance matter so much?

Because a radio signal spreads out as it travels. In open air, the power reaching a device falls with the square of the distance: twice as far gets a quarter of the power, and four times as far gets a sixteenth. Walls, floors, mirrors, metal and water then absorb or bounce part of what's left; brick, concrete and the metal in some insulation are much worse than wood or plasterboard, and a fish tank or a refrigerator between you and the router is surprisingly effective at blocking it.

A weaker signal doesn't just drop out. The radios step down to simpler, slower patterns that survive noise better. Here is how that plays out in one home with a 300 megabits per second (Mbps) internet plan:

Where the laptop is	What limits it	Roughly what you get
Same room as the router, 5 GHz	The internet plan	About 300 Mbps
Two rooms away, through one wall	Still the internet plan	About 300 Mbps
Far bedroom, through brick, falls back to 2.4 GHz	The Wi-Fi link, now the slowest step	Perhaps 50 to 100 Mbps

The numbers are illustrative, but the lesson holds: a connection is only as fast as its slowest step. In the near rooms, upgrading the router does nothing, because the plan is the limit. In the far room, a faster plan does nothing, because the Wi-Fi is. A second access point, or a mesh system of several units that hand devices between them, fixes that room; a bigger plan doesn't.

Is Wi-Fi the same as the internet?

No, and the confusion causes a lot of wasted fixes. Wi-Fi is the link inside your home; the internet is the global network beyond it. Three different jobs are involved, often in one box:

Device	What it does
Modem	Connects your home to your internet provider's line: cable, fiber or phone line.
Router	Joins your devices into one home network, gives each a private [[what-is-an-ip-address
Wireless access point	The radio part: turns the router's network into Wi-Fi. Usually built into the router.

That is why a phone can show full Wi-Fi bars and "no internet": the radio link to the router is fine, but something beyond it, the modem, the provider's line or the provider itself, is down. Restarting the modem fixes some of those; moving closer to the router fixes none. Past the modem, data travels across the internet by cable and fiber, with no Wi-Fi involved at all. Mobile data is different again: 5G is a radio link to a phone company's tower, using frequencies the company has licensed, while Wi-Fi uses frequencies anyone may use without a license.

What do Wi-Fi 6 and Wi-Fi 7 mean?

The standards behind Wi-Fi are written by an engineering body, the IEEE, under the name 802.11, with a letter or two for each version. The industry group that certifies devices, the Wi-Fi Alliance, gave them plain numbers on 3 October 2018: Wi-Fi 4 for 802.11n, Wi-Fi 5 for 802.11ac and Wi-Fi 6 for 802.11ax.

Name	Standard	Arrived	What it added
(none)	802.11	1997	The first standard: up to 2 Mbps
(none)	802.11b	1999	11 Mbps on 2.4 GHz; the "Wi-Fi" brand begins
Wi-Fi 4	802.11n	2009	Several antennas at once; both 2.4 and 5 GHz
Wi-Fi 5	802.11ac	2013	Much faster on 5 GHz
Wi-Fi 6 and 6E	802.11ax	2019 to 2021	Better in crowded places; 6E adds the 6 GHz band
Wi-Fi 7	802.11be	2024	320 MHz-wide channels in 6 GHz, and using several bands at once

The headline speeds on boxes are theoretical maximums that no home reaches. What a newer version mostly brings is better behavior when many devices share the air. In 2026 the next version, 802.11bn, informally Wi-Fi 8, was still a draft at the IEEE's working group, aimed at reliability rather than peak speed. A new router only helps if your devices support the same version.

Is Wi-Fi safe to use?

Your own network is as safe as its password and its security setting. Anyone in range can pick up the radio waves, so Wi-Fi encrypts them: use WPA3, which the Wi-Fi Alliance now requires for certified devices, or WPA2 on older equipment, with a long password, and keep the router's software up to date. Public networks in cafés and airports are a different matter, because you don't control them and others share them. Most websites and apps now encrypt their own traffic, which protects the content, and a VPN adds a further layer on networks you don't trust.

Check yourself

• Without looking back: why does a 6 GHz signal reach less far than a 2.4 GHz one, and what does it offer in return?
• What do the modem, the router and the access point each do?
• Your phone shows full Wi-Fi bars but no internet. Where is the problem, and where isn't it?

Sources

• Wi-Fi Alliance introduces Wi-Fi 6 — Wi-Fi Alliance, 2018
• Wi-Fi CERTIFIED 6 — Wi-Fi Alliance
• Wi-Fi CERTIFIED 7 — Wi-Fi Alliance
• Security — Wi-Fi Alliance
• IEEE 802.11 Wireless LAN Working Group — IEEE
• IEEE 802.11 — Wikipedia