LM324 DIP14 through hole is a 14pin IC consisting of four independent operational amplifiers (op-amps) compensated in a single package.
Op-amps are high gain electronic voltage amplifier with differential input and, usually, a single-ended output.
The output voltage is many times higher than the voltage difference between input terminals of an op-amp.
These op-amps are operated by a single power supply LM324 and need for a dual supply is eliminated.
They can be used as amplifiers, comparators, oscillators, rectifiers etc.
The conventional op-amp applications can be more easily implemented with LM324.