An integrated circuits,is just a “ready-made” circuit,built into aconvenient ‘plug in’,standard sized box. It’s just made of really small component like transistors/resistor/diodes onto a tiny ready-made circuit
“Integrated circuits(IC)”,also called microelectronic circuit or chip, an assembly of electronic components, fabricated as a single unit, in which miniaturized active devices (e.g., transistors and diodes) and passive devices (e.g., capacitors and resistors) and their interconnections are built up on a thin substrate of semiconductor material (typically silicon). The resulting circuit is thus a small monolithic “chip,” which may be as small as a few square centimetres or only a few square millimetres. The individual circuit components are generally microscopic in size.