A switch works by interrupting current flow around an electrical circuit. A basic switch is a binary device: it is either open (off) or closed (on). The simplest type of switch is one that comprises two metal strips that are brought into contact by a spring or some other form of actuating mechanism.
The spring or actuating mechanism inside the switch pushes the metal strips together so that they touch. The switch is then said to be on, and electric current flows around the circuit. When the spring is released so that it does not push against the metal strips, the switch is open and the current flow is cut off. Switches come in many types. Toggle switches are designed to be operated by people and are some of the most common switches. A typical example of a toggle switch is a household light switch. Push-button switches are also relatively common; this type of switch uses a push-button and some type of momentary configuration to actuate the circuit. Selector switches use a rotary knob or some form of lever to actuate, and they may be built with a spring mechanism for momentary operation. Other types of switches include the joystick switch, proximity switch, speed switch and pressure switch.