Very-large-scale integration (VLSI) is the process of creating an integrated circuit (IC) by combining billions of transistors into a single chip. VLSI began in the 1970s when complex semiconductor and communication technologies were being developed.

The microprocessor is a VLSI device. Before the introduction of VLSI technology most ICs had a limited set of functions they could perform. An electronic circuit might consist of a CPU, ROM, RAM and other glue logic. VLSI lets IC designers add all of these into one chip.