white bakelite over-centre rotary two-way switch

This switch can be installed on a two-way or simple circuit.

What is a two-way switch?
Two-way switch, providing control of a light from two locations.
A two-way circuit is an electrical circuit that allows a lamp to be switched on or off from two switches, for example, a switch at each end of a corridor for the same lighting point.

What is a simple switch?
The simple switch, on the other hand, is used to switch a light on or off from a single location in the room (usually at the entrance to the room).