The thermionic triode, a vacuum tube invented in 1907, enabled amplified radio technology and long-distance telephony. The triode, however, was a fragile device that consumed a substantial amount of power. In 1909,

Before transistors were developed, vacuum (electron) tubes (or in the UK "thermionic valves" or just "valves") were the main active components in electronic equipment.
Advantages
The key advantages that

Three major identification standards are used for designating transistor devices. In each, the alphanumeric prefix provides clues to the type of the

Transistors are the key active components in practically all modern electronics. Many thus consider the transistor to be one of the greatest inventions of the 20th century.

A transistor can use a small signal applied between one pair of its terminals to control a much larger signal at another pair of terminals. This property is called gain. It can produce a stronger output signal, a voltage or current, which is proportional to a weaker

Classification
Transistors are categorized by
• Structure: MOSFET (IGFET), BJT, JFET, insulated-gate bipolar transistor

Semiconductor material
The first BJTs were made from germanium (Ge). Silicon (Si) types currently predominate but certain advanced microwave and high