An operational amplifier, or op-amp, is a type of amplifier that is used in a wide variety of electronic circuits. It is a high-gain, direct-coupled amplifier that can be used to amplify AC or DC signals over a wide frequency range. Operational amplifiers are commonly used in RF circuits to perform a variety of functions, such as amplifying weak signals, filtering out unwanted signals, or providing gain control. They are also used in many other types of electronic circuits, such as audio circuits, control systems, and signal processing circuits. Operational amplifiers are typically used in combination with other components, such as resistors and capacitors, to create a complete circuit.