An integrated circuit (IC) is a device that combines many different types of circuit elements in a single, solid piece of material. "To integrate" means "to bring together into a whole"; in constructing an "integrated" circuit, active elements (such as transistors and diodes) and passive elements (such as capacitors and resistors) are fabricated in the superficial layers of a single crystal of silicon or other semiconducting material. More than any other single invention, the integrated circuit has made possible the microelectronics revolution of the late 20th century and beyond.

A typical IC microprocessor is smaller than a match head while containing millions of transistors and other components. The microprocessor is the heart of the personal computer and executes hundreds of millions of instructions per second. The number of transistors and other electronic components on an IC is often used to classify it. ICs may be defined...