A SPDT switch, or Single Pole Double Throw switch, is an electrical component that can connect one input to one of two outputs. It has three terminals: one common terminal and two output terminals. When the switch is toggled, it either connects the common terminal to the first output or to the second output, allowing for versatile control in circuits. SPDT switches are commonly used in various applications, such as in lighting systems to control multiple light sources or in electronic devices to select between different modes. Their simple design makes them easy to use and integrate into different projects.