Integrated Circuits also known as ICs. A reduce size, weight, and power requirements of modern electronic equipment. From vacuum tube to transistors, and now IC’s . ICs are actually microelectronic circuits. It contains small electronic components such as diode, transistors, and capacitors which is visible only to a microscope. There are two classification of an IC, Linear ICs and the other one is Digital ICs.
Digital ICs are use in computers, microprocessors, memory chips, calculator, and digital clocks as well as many other digital device. Digital ICs process only on/off signals or using binary mathematics to process “one” and “zero” signals.
Linear ICs are use in analog type circuit like audio amplifiers, voltage regulator, operational amplifiers, and some radio frequency circuits. Most linear ICs are low-power device with power dissipation rating lower than 1W.
History of ICs from wikipedia
Early developments of the integrated circuit go back to 1949, when the German engineer Werner Jacobi (Siemens AG) filed a patent for an integrated-circuit-like semiconductor amplifying device  showing five transistors on a common substrate arranged in a 2-stage amplifier arrangement. Jacobi discloses small and cheap hearing aids as typical industrial applications of his patent. A commercial use of his patent has not been reported.
The idea of the integrated circuit was conceived by a radar scientist working for the Royal Radar Establishment of the British Ministry of Defense, Geoffrey W.A. Dummer (1909–2002), who published it at the Symposium on Progress in Quality Electronic Components in Washington, D.C. on May 7, 1952. He gave many symposia publicly to propagate his ideas. Dummer unsuccessfully attempted to build such a circuit in 1956.
A precursor idea to the IC was to create small ceramic squares (wafers), each one containing a single miniaturized component. Components could then be integrated and wired into a bidimensional or tridimensional compact grid. This idea, which looked very promising in 1957, was proposed to the US Army by Jack Kilby, and led to the short-lived Micromodule Program (similar to 1951′s Project Tinkertoy). However, as the project was gaining momentum, Kilby came up with a new, revolutionary design: the IC.
Robert Noyce credited Kurt Lehovec of Sprague Electric for the principle of p-n junction isolation caused by the action of a biased p-n junction (the diode) as a key concept behind the IC.
Jack Kilby’s original integrated circuit
Jack Kilby recorded his initial ideas concerning the integrated circuit in July 1958 and successfully demonstrated the first working integrated circuit on September 12, 1958. In his patent application of February 6, 1959, Kilby described his new device as “a body of semiconductor material … wherein all the components of the electronic circuit are completely integrated.” Kilby won the 2000 Nobel Prize in Physics for his part of the invention of the integrated circuit.
Robert Noyce also came up with his own idea of an integrated circuit half a year later than Kilby. Noyce’s chip solved many practical problems that Kilby’s had not. Noyce’s chip, made at Fairchild Semiconductor, was made of silicon, whereas Kilby’s chip was made of germanium.
One of the most advance integrated circuit are the microprocessor or “core”. It is responsible in controlling modern digital device such as computers, cellular phones, and some digital devices. The performance of ICs is high because the small size allows short traces which in turn allows low power logic to be used at fast switching speeds. Migration of the ICs in a smaller scale had been consistent over the years, allowing more components to be place in one single chip. The number of transistors in an integrated circuit doubles every two years. As the feature size shrinks, almost every function and features improves.