A brief history of networks

The modern internet has revolutionized how we communicate with one another. However, it had humble beginnings in the Victorian era. One of the earliest precursors to the internet was telegraph networks which were operational as early as 1850. Back then, it used to take 10 days to send a message from Europe to North America by sea. Telegraph networks reduced that to 17 hours. By the late 19th century, the telegraph was a fully successful communication technology that was used widely in the two world wars. Around that time, people started building computers to help in cracking enemy codes. Unlike our modern mobile phones and laptops, those computing machines were often huge and needed specialized environments to be able to operate smoothly. Thus, it was necessary to put those in special locations while the operators would sit on a terminal. The terminal needed to be able to communicate with the computer over short distances. A number of local area networking technologies enabled this, the most prominent one being Ethernet. Over time, these networks grew and by the 1960s, some of these networks were being connected with one another to form a larger network of networks. The Advanced Research Projects Agency Network (ARPANET) was established in 1969 and it became the first internetwork that resembles the modern internet. Around 1973, there were a number of such internetworks all around the world, each using their own protocols and methods for communication. Eventually, the protocols were standardized so that the networks could communicate with each other seamlessly. All of these networks were later merged to form what is the internet today.

Since networks evolved in silos all around the world, they were often organized according to geographical proximity. A Local Area Network (LAN) is a collection of host machines in small proximity like a building or a small neighborhood. A Wide Area Network (WAN) is one that connects multiple neighborhoods; the global internet is at the top of the hierarchy. The next picture shows a map of the ARPANET in 1977. Each node in this map is a computer (a server, in today's terms). Most of these were located in large universities like Stanford or at national laboratories like Lawrence Berkeley (source: https://commons.wikimedia.org/wiki/File:Arpanet_logical_map,_march_1977.png).