Two way switching means having two or more switches in different locations to control one lamp. This arrangement is often found in stairways, with one switch upstairs and one switch downstairs or in long hallways with a switch at either end.
source/image(PrtSc): The Engineering Mindset
They are wired so that operation of either switch will control the light.How to wire 2 way light switch, in this video we explain how two way switching works to connect a light fitting which is controlled with two light switches.video by: The Engineering Mindset
We look at the EU colour coding wires and explain the different ways to connect the lighting circuit.A Two Way light switch is a simple single pole “changeover” switch with three terminals. These are typically labelled COM, L1, and L2 (Some may label the L1 and L2 positions as “1 Way” and “2 Way”).
In one switch position the COM terminal is connected to L1. In the other switch position it changes over so that COM is connected to L2. The design is a “break before make” type, such that the connection to the first terminal is disconnected before the connection to the new one is made.