system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: How can you have two electrical switches that perform the same role independent of the other switch?

In many houses you have, for example, a corridor with two light switches at either end. When you turn either switch on/off then the light turns on. Similarly, either will turn the light off, independent of the other switch's position. This does not seem to follow either series or parallel circuit logic, so how can this be?
gpt
It's called a three-way switch. The two light switches are wired up to each other, and also to the light. There's an extra piece of wire connecting the two switches to each other.

When both switches are on, the light goes on. When both switches are off, the light goes on. If one switch is off and the other switch is on, the light turns off.

That way you can control the light from either side. It doesn't matter if an individual switch is on or off - they just need to be in the same state as the other switch.