Op Amps (Operational Amplifiers) are composed of two inputs, an output, and positive and negative power supply pins.
Op Amps can be used in many different set-ups, among them being: Voltage Comparators, Inverting and Non-inverting amplifiers, Summing amplifiers, and Difference amplifiers.
In Op Amps, the voltage of the output is dependent on the voltages of the two inputs. If the Inverting input is higher, the output will be the same as the negative supply. If the Non-Inverting input is higher, the output will be the same as the positive supply.
Pins 2, 3, 4, 6, and 7 are the only pins which need to be connected to the circuit in order to use the Op Amp.