Transistor

Discovery of the transistor was publicly announced in 1948. Before this time, electronics had depended almost exclusively upon vacuum tubes for amplification and switching actions. Vacuum tubes are relatively bulky, short-lived, and wasteful of power; transistors are small—from peanut-size to only a few molecules across—long-lived, and dissipate far less power. Transistors are also resistant to mechanical shocks and can be manufactured by the millions on tiny semiconductor crystals (chips) using optical techniques. Transistors and related solid-state (i.e., entirely solid) devices have replaced vacuum tubes except for specialized applications, especially those involving high power.