The history of the internet as we know it today starts with networks. All networks strive to answer the question of how two machines can communicate with each other. Several interesting networks existed before the modern era of computer networks, such as the telephone network, but we will focus on the modern computer network. But what exactly are computer networks? I’m glad you asked. A computer network consists of a set of nodes linked to each other so they can exchange information. Desktop computers, laptops, and mobile devices are examples of nodes, but they can also include machines such as servers, switches, routers, and much more. Depending on their function, some machines enable other nodes in the network to communicate with each other better.

The first large-scale computer network was ARPAnet (Advanced Research Projects Agency Network) in 1969 developed by DARPA (Defense Advanced Research Projects Agency), an agency of the United States Department of Defense. There have been other computer networks such as RAND, NPL, and CYCLADES, but they never reached a mass market. ARPAnet was the first packet-switched network with distributed control to implement TCP/IP. It is at the core of today’s internet.

Packet switching is a technique of sending small chunks of information called packets over a set of cables and computers. Rather than relying on a dedicated line or switching operators, as in the old telephone networks, packets can be routed through the network and assembled at the receiver end.

The protocol that ensures every packet arrives safely is called TCP (Transmission Control Protocol). In order to build a decentralized network, different routing protocols were developed so that even if one node was unavailable, the message would still be routed through. In the beginning, all nodes knew each other’s addresses. However, as smaller networks joined the network, additional protocols had to be created so that computers didn’t need to know each other’s addresses. When the IP standard was developed to ensure compatibility between networks, it was added to form TCP/IP.

The ARPAnet grew as more computers were added, reaching a point where even when the ARPAnet hardware was removed in the late 1980s, the network remained large enough to survive. With the arrival of commercial internet service providers (ISPs), the internet evolved into what it is today.

The most important thing to take away from this brief history lesson is that packets still run through our networks today and that the internet is made up of smaller networks that are interconnected. The files we send over the Internet are broken down into smaller pieces called packets and are sent by a variety of computers. When we send a big image or multiple files it affects the performance of our website (especially on slow connections). For a better user experience, we want to send as little data as possible to ensure that the site loads as quickly as possible. This is measured in latency. Latency refers to the time it takes for data to travel between a source and a destination. We will explore what optimizations can be made to increase website speed later in this series of articles.