A Single Pole Single Throw (SPST) switch is a basic type of electrical switch that controls a single circuit. It has two positions: ON and OFF. When the switch is in the ON position, it allows current to flow through the circuit, powering connected devices. In the OFF position, the circuit is open, stopping the flow of electricity. SPST switches are commonly used in various applications, such as lighting and simple electronic devices. They are straightforward to operate and are often found in household items like lamps and fans. Their simplicity makes them a popular choice for basic on/off control.