How do I hook up a 3 way light switch?

In this regard, what is the common wire in a three way switch?

The switch wiring for three-ways is normally Red, Black, and White. If the White is correctly used for neutral, the connected switching wires are Red and Black. The White (neutral) is often referred to as Common, but the colored wires are both used as Hot wires, alternately as the possible switch positions are made.

Likewise, does it matter which wire goes where on a light switch? Properly you should have a black always hot wire bringing power in and a red wire going to the light. Red means the line may be switched. Sometimes electricians go cheap and use black instead of red. If your switch has a “LINE” marking, the always hot wire goes to this.

Moreover, how does a 3 way light switch work?

"3-way" is the electrician's designation for a single pole double throw (SPDT) switch. The switches must create a complete circuit for current to flow and the bulb to light. When both switches are up, the circuit is complete (top right). When both switches are down, the circuit is complete (bottom right).

Is the common wire red or black?

The faceplate of a single, one-way switch has two terminals: "L1" is the terminal to which the neutral core wire is attached - the blue wire (traditionally black, before the change). "COM" or "Common" is the terminal to which the live core wire is attached - this is the brown wire (formerly red).