Switch is a device for making or breaking an electric circuit, or for selecting between multiple circuits.

There are various kinds of switch

Dip Switch
A small switch used to select the operating mode of a device, mounted as a dual in-line package. DIP switches can be either sliding or rocker switches, and they are often grouped for convenience. They are used in printed circuit boards, dot-matrix printers, modems, and many other peripheral devices.

Toggle Switch
Switch that is turned on by moving a lever to the correct position.

Three way Switch
Electrical switches installed in pairs to allow a light or appliance to be controlled from to locations.

Mercury Switch
Mercury switch" means a mercury-added product or device that opens or closes an electrical circuit or gas valve. "Mercury switch" includes mercury float switches actuated by rising or falling liquid levels, mercury tilt switches actuated by a change in the switch position, mercury pressure switches actuated by a change in pressure, mercury temperature switches actuated by a change in temperature and mercury flame sensors.

Digital Switch
In the field of telecommunications, a telephone exchange (US: telephone switch) is a piece of equipment that connects phone calls. It is what makes your phone calls "work" in the sense of making connections and relaying the speech information.