Semiconductors are materials which have a conductivity between conductors (general metals) and nonconductors or insulators (such as ceramics). Semiconductors are made from pure elements, typically silicon or germanium, or compounds such as gallium arsenide. In a process called doping, small amounts of impurities are added to pure semiconductors causing large changes in the conductivity of the material.
Due to their role in the fabrication of electronic devices, semiconductors are an important part of our lives. Imagine life without electronic devices. There would be no radios, not TV's, no computers, no video games, and poor medical diagnostic equipment. Although many electronic devices could be made using vacuum tube technology, the developments in semiconductor technology during the past 50 years have made electronic devices smaller, faster, and more reliable. Think for a minute of all the encounters you have with electronic devices. How many have you seen or used in the last twenty-four hours? Each has important components that have been manufactured with electronic materials.