Field Effect Transistors, or FETs, are semiconductor devices used to control electrical signals. They operate by using an electric field to influence the flow of current. FETs have three main terminals: the source, gate, and drain. The gate terminal regulates the current between the source and drain, allowing for efficient signal amplification and switching. There are several types of FETs, including MOSFETs (Metal-Oxide-Semiconductor FETs) and JFETs (Junction FETs). MOSFETs are widely used in digital circuits and power applications due to their high efficiency and fast switching speeds. FETs are essential components in modern electronics, enabling the functionality of devices like computers and smartphones.