What is an operational amplifier?

An operational amplifier (op-amp) is an integrated circuit designed for processing analog signals. It operates by amplifying the voltage difference between its two input terminals, making it a differential amplifier. Because it is direct-coupled, it can amplify both DC and AC signals. Ideally, an op-amp has infinite input impedance (so it draws almost zero current from the source circuit) and zero output impedance (so it can easily drive other circuit components). Real-world op-amps closely approximate these ideals, having very high input impedance and very low output impedance. These characteristics make op-amps incredibly versatile, allowing their behavior to be precisely controlled by adding external feedback components like resistors and capacitors.