The internet

Precursors
The concept of data communication – transmitting data between two different places through an electromagnetic medium such as radio or an electric wire – pre-dates the introduction of the first computers. Such communication systems were typically limited to point to point communication between two end devices. Semaphore lines, telegraph systems and telex machines can be considered early precursors of this kind of communication. The telegraph in the late 19th century was the first fully digital communication system.
Early computers had a central processing unit and remote terminals. As the technology evolved, new systems were devised to allow communication over longer distances (for terminals) or with higher speed (for interconnection of local devices) that were necessary for the mainframe computer model. These technologies made it possible to exchange data (such as files) between remote computers. However, the point-to-point communication model was limited, as it did not allow for direct communication between any two arbitrary systems; a physical link was necessary. The technology was also considered unsafe for strategic and military use because there were no alternative paths for the communication in case of an enemy attack.
Information theory
Fundamental theoretical work in data transmission and information theory was developed by Claude Shannon, Harry Nyquist, and Ralph Hartley in the early 20th century. Information theory, as enunciated by Shannon in 1948, provided a firm theoretical underpinning to understand the trade-offs between signal-to-noise ratio, bandwidth, and error-free transmission in the presence of noise, in telecommunications technology.^[18]
Semiconductor technology
The development of transistor technology was fundamental to a new generation of electronic devices that later affected almost every aspect of the human experience.^[19][20][21] The long-sought realization of the field-effect transistor, in form of the MOS transistor (MOSFET), by Mohamed Atalla and Dawon Kahng at Bell Labs in 1959,^[22][23][24] brought new opportunities for miniaturization and mass-production for a wide range of uses. It became the basic building block of the information revolution and the information age,^[25][26] and laid the foundation for power electronic technology that later enabled the development of wireless Internet technology.^[27][28][29] Network bandwidth has been doubling every 18 months since the 1970s, which found expression in Edholm's law,^[30] similar to the scaling expressed by Moore's law for semiconductors.
Development of wide area networking
With limited exceptions, the earliest computers were connected directly to terminals used by individual users, typically in the same building or site.
Wide area networks (WANs) emerged during the 1950s and became established during the 1960s.