This chapter begins with the discovery of thermionic emission and outlines the evolution of vacuum tubes (diodes, triodes, tetrodes, pentodes etc.). It traces the development of radio communication technologies (amplitude and frequency modulations) and the discovery of intrinsic and extrinsic semiconductors. The 1947 invention of the point-contact transistor by Bardeen and Brattain, and Shockley’s development of the junction transistor marked the beginning of solid-state electronics. The progression from discrete components to integrated circuits (ICs), including MOS, MOSFETs and CMOS, led to large-scale integration (LSI) and very large scale integration (VLSI) with hundreds of transistors on a single MOS chip. A brief history of the discovery of inventions of various semiconducting devices is presented. The history of computers, software development, television, optoelectronics (LCD, LED, OLED), lasers and masers, and internet protocols is detailed, including the evolution of smart phones. The emergence of nanoelectronics and quantum dot lasers is briefly introduced.