The diagrams below show the conventional wiring for 3 way switches. The thing to remember about 3 way switch wiring is that 3 way switches are always used in pairs.

Wiring A 3 Way Switch
3 way switch meaning. These switches do not have an onoff position like single pole switches. 3 way switches are used to control lights with two switches. Such markings are not needed with this type of switch as they are. Controlling a light with three or more switches. This page describes how to use 3 way and 4 way switches to control lights. There are three screw terminals on the body of the switch in addition to the green grounding.
Electric switch electrical switch switch control consisting of a mechanical or electrical or electronic device for making or breaking or changing the connections in a circuit. For more than two switches one or more 4 way switches are added. There are no onoff markings on the switch toggle. It is important to understand how these are wired before attempting to troubleshoot or replace. Used to control a circuit from two different locations. A three way light switch is different than a traditional single pole light switch as it contains an extra screw to connect an extra wire.
There are two clear giveaways that identify a switch as being a three way type. A regular switch has only two connections and simply cuts the flow of electricity through the switch or allows the current to pass through it. An electric switch having three terminals used to control a circuit from two different points. This is known as the common screw and its usually black instead of brass or silver. A third type is the four way switch which is used in conjunction with two three way switches to control lighting from more than two locations. Definition of three way switch.
In other words if a circuit has 3 way switches it always has two of them. If there are other switches on the same circuit these must be 4 way switches. Three way switch an electric switch that has three terminals. Another dead giveaway of a three way switch is the absence of on and off markings. The 3 way switch was originally developed to allow users to control a light from two different locations. This requires a special switch.
3 way switches are not used on the same circuits with standard single pole switches. This configuration may be used in open plan homes or in large kitchens or great rooms where a central bank of lighting fixtures might be controlled from more than two entry points. How 3 way and 4 way switch circuits work controlling a light with two or more switches. The three way switch is a variation of the standard single pole switch which controls a light only from one location.