Regulator

A regulator is an electronic component that is used to maintain a constant voltage or current in a circuit. It works by controlling the amount of current that flows through a circuit, either by dropping excess voltage across a resistor or by using a transistor to regulate the current. 
Voltage regulators are commonly used in electronic circuits to ensure that the voltage supplied to sensitive components remains constant, even as the input voltage fluctuates. They are used in a wide range of applications, from simple battery-powered devices to complex power supplies for industrial and commercial equipment.
Current regulators, on the other hand, are used to maintain a constant current in a circuit. They are commonly used in applications such as LED lighting and motor control, where precise control over the current is critical to ensure proper operation.