The integrated circuit operational amplifier (op-amp) is an extremely versatile electronic
device, which is encountered in a wide variety of applications ranging from consumer
electronics (stereos, VCR’s) to complex commercial applications and industrial controls. This
versatility stems from the very high voltage gain (100,000 and higher for the 741) together with
high input resistance (typically 1 MΩ) and low output resistance (typically 50Ω). These
characteristics allow use of large amounts of feedback from output to input with the result that
the desired output signal is dependent only on the external components.