what is wafer ?

A wafer is a thin slice of semiconductor material, such as a crystalline silicon, used in electronics for the fabrication of integrated circuits. It is used in photovoltaics for conventional wafer-based solar cells. A wafer is also called a slice or substrate, wafer fabrication is a procedure composed of many repeated sequential processes to produce complete electrical or photonic circuits. Wafer are used in the production of radio frequency (RF) amplifiers, LEDS, Optical computer components, and CPUs for computers.