A triac is a type of semiconductor device that can control electrical power. It functions by allowing current to flow in both directions when triggered, making it useful for alternating current (AC) applications. Triacs are commonly found in light dimmers, motor speed controls, and heating systems. When a small voltage is applied to its gate terminal, a triac turns on and remains conducting until the current drops below a certain level. This ability to switch on and off makes triacs efficient for managing power in various electronic devices, contributing to energy savings and improved control.