Electronic switch

In electronics, an electronic switch is an electronic component or device that can switch an electrical circuit, interrupting the current or diverting it from one conductor to another. Electronic switches are considered binary devices because they can be on or completely off. When an electronic switch is on, it is considered closed in a circuit. When the switch is classified as off the switch is open in the circuit. 
Typically, electronic switches use solid state devices such as transistors, though vacuum tubes can be used as well in high voltage applications. Electronic switches also consist of complex configurations that are assisted by physical contact. Physical contact typically comes from pressing or flipping a switch with your hand, but other forms of contact like light sensors and magnetic field sensors are used to operate switches. 
Switch Types.
Different kinds of switches are used for different applications in today's devices. Switches operated by a person are called "hand switches", hand switches consist of many types like toggle switches, pushbutton switches, selector switches, and joystick switches. Another popular form of switch is a motion switch, these are typically called "limit switches". Limit switches are used to limit the motion of a machine. Limit switches are usually used for preventive safety measures so that a machine will cut off past a specified point. Two of the most common limit switches are "lever actuator switches" and "proximity switches".
In industrial processes, process switches are used to monitor physical quantities. Switches such as "speed", "pressure", "temperature", "liquid level", "liquid flow", and "nuclear level switches" are used to monitor vital information so that a process stays in control and never exceeds safety regulations. 
The most widely used electronic switch in digital circuits is the metal–oxide–semiconductor field-effect transistor (MOSFET).
Switch Applications.
Electronic switches are used in all kinds of common and industrial applications. Household applications consist of simple hand switches like toggle switches and push-button switches. Turning on lights, opening garage doors, and rolling down a car window all use simple switches. Industrial applications for electronic switches consist of more complex systems like conveyors, furnaces, welders, and water pumps. With complex systems, a variety of switches can be used to complete a task, but due to the advantages or disadvantages of certain switch types, the switch should be chosen based on graded efficiency and reliability metrics. 