Transistor
Developed by John Bardeen, Walter Brattain, and William Shockley at the Bell Laboratories on December 23, 1947. The transistor (short for transfer resistance) is made up of semi-conductors and is a component used to control the amount of current or voltage or used for amplification/modulation or switching of an electronic signal.
In the picture to the right, are examples of what transistors may look like.
In 1954, IBM announced it was no longer planning to use vacuum tubes in its computers and introduced its first computer that had 2000 transistors. Transistors replaced vacuum tubes and today are found in virtually all electronic devices.
Also see: Electronics definitions, IC, Moore's Law, Power definitions, Solid-state device