One of most popular IC chips is the LM555
The IC 555 is used in LED flashers, oscillators, and PWM circuits.

Integrated circuit: a chip made up of several electronic components such as resistors, capacitors, inductors, and transistors. ICs are built in a small block or chip of semiconductor material, usually silicon.
ICs are widely used in microprocessors, computers, computer networks, frequency counters and digital
signal processors.
The IC 555 is used in LED flashers, oscillators, and PWM circuits.