A time switch is an electric switch that switches after the time period that the user has set. It can be mechanical or electrical.
Images for kids
A simple 24-hour cyclical electromechanical time switch with a French CEE 7/5 socket
A 24-hour cyclical electromechanical UK time switch showing current time 06:15 and set to be on from 07:00 to 07:45 and 20:00 to 22:00.
Digital in-wall timer switch with battery for uninterrupted time keeping