Hi Angela, this is a great question about an old analog type device.
An operational amplifier (often op-amp or opamp) is a DC-coupled high-gain electronic voltage amplifier with a differential input and, usually, a single-ended output. An op-amp produces an output potential (relative to circuit ground) that is typically hundreds of thousands of times larger than the potential difference between its input terminals. It is made up of many different PNP and NPN junctions to provide an Inverting and a non-Inverting input to a single output. The ua741 was first developed back in 1968 and is still in production today. Vacuum tube type Op-Amps were first developed back in 1941 by Karl D. Swartzel Jr. of Bell Labs.