As the name suggests, An Integrated Circuit (IC), is a summation of electronic elements of a functional circuit available in small package.
Integrated Circuit (IC) is also called as Chip or Microchip or Silicon Chip,
In other words, IC is a small semiconductor wafer, usually made of silicon, on which multiple tiny transistors, resistors, diodes, capacitors etc., are fabricated to form a useful or functional circuit, which is enclosed in a plastic or ceramic material with the connecting pins on its periphery (or surface).
An IC can do following functions in single or combination of counter, timer, amplifier, voltage regulation, oscillator, memory, ADC, DAC , arthematics etc. A microprocessor or a micro-controller also falls under IC catagory.
The complexity and functionality of an IC depends on the number of transistors and associated electronic components used on a silicon wafer. The following is the types of integration and associated number of transistors used in the IC.
ICs are available in various packages with specific name. The package name indicates the size, shape, position of pins, pin out format etc.
All Micro-Processors, Micro-Controllers, Voltage Regulators, Op-Amps etc., are ICs (Integrated Circuits) only