The Transistor (1947)

The transistor, invented at Bell Labs in 1947 by Bardeen, Brattain, and Shockley, replaced the vacuum tube as the basic unit of electronic amplification and switching. It enabled compact, reliable, affordable electronics — the integrated circuit, the microprocessor, the personal computer, the smartphone, and the AI revolution. Every digital device in existence today is fundamentally a collection of transistors; a modern phone contains approximately 15 billion.