Toggle switch, also known as a switch, is an electronic switch. It usually consists of a button and a corresponding circuit. The button is typically composed of a spring and a movable contact. When the button is pressed, the contact touches the fixed contact, closing the circuit; when the button is released, the spring returns the contact to its original position, breaking the circuit. Toggle switches are commonly used in control circuits for electronic devices such as TVs, stereos, and computers, with advantages such as small size and convenience. There are three common types of toggle switches: single-pole single-throw (SPST) ,single-pole double-throw(SPDT) and double-pole double-throw (DPDT).