how does wifi go through walls?

1radio waves

Your router doesn't send a beam like a flashlight — it sends radio waves, spreading out in every direction like ripples on a pond.

2wavelength

Radio waves are just like light and microwaves, but much longer — WiFi waves are about 12 centimeters tip to tip, big enough to bend and squeeze past small obstacles.

3wall meets wave

Hit a wall, and three things happen: some wave bounces off, some gets soaked up as heat, and some pushes on through weaker than before.

4material matters

Drywall barely dents the signal — it's mostly air and paper. But thick concrete, brick, or a metal stud can block most of the wave, or even reflect it entirely.

5signal fades

That's why WiFi fades room to room but doesn't vanish — every wall steals a little strength until there's not enough signal left to hear.