Unit 5 network and web technologies

How did the Internet develop from standalone computers?
Originally, computers were designed to be used as standalone machines where individuals worked in isolation on their own tasks. Eventually, the idea emerged to link two computers together to share files and resources, which marked the beginning of computer networking. This innovation expanded rapidly: instead of simply linking two computers, networks grew to link many machines together, enabling shared data, shared resources, and remote access. Today, the Internet represents the largest and most complex network, connecting countless smaller networks worldwide.

What is the Internet?
The Internet is a massive global network of interconnected networks. It functions as a Wide Area Network (WAN), meaning it spans extensive geographic regions. It is conceptually similar to a smaller home network, except on a much larger scale. It allows computers across the world to communicate using common protocols. The World Wide Web (WWW) operates on top of the Internet: it is a collection of documents and resources that are accessed via the Internet using web browsers. However, the Internet also carries other kinds of data beyond the web, such as email, file transfers, video conferencing, and streaming services.

How is traffic directed on the Internet?
The Internet directs data similarly to how a road network directs vehicles. Data is divided into packets, each labelled with a destination address (IP address). Routers read these addresses and forward packets along the best possible route. If a direct route is unavailable or a link fails, packets are automatically rerouted through alternate paths. This decentralised routing system ensures that data can always reach its destination even if some parts of the network fail, which makes the Internet highly fault-tolerant and resilient.

What is the Internet backbone?
The Internet backbone is the central infrastructure of the Internet. It consists of ultra-high-speed, dedicated fibre-optic connections that link large, high-capacity networks known as Network Access Points. These backbone networks are distributed across major global locations and are connected to regional networks, which are usually controlled by Internet Service Provider (ISPs). ISPs then provide Internet access to local ISPs and individual end users. This layered hierarchy allows data to travel efficiently between continents and countries. If a backbone link fails (for example, a fibre cable is damaged), the Internet automatically reroutes traffic through other backbone routes to maintain connectivity.

How do undersea cables fit into the structure?
Much of the Internet backbone consists of undersea fibre-optic cables that connect continents. These cables carry enormous amounts of data at high speeds. If a cable between two locations becomes unavailable (for example, if all connections from France to the United States fail), data will reroute through other countries’ backbone connections. This design prevents a single point of failure from cutting off communication between major regions. This fault-tolerant approach is fundamental to the stability of global Internet infrastructure.

Summary

The Internet grew from simple file-sharing between two standalone computers into a vast global network of interconnected systems. It is a massive WAN consisting of smaller networks linked together. Data is routed dynamically like vehicles on a road network, ensuring delivery even if some routes fail. The core of this system is the Internet backbone — a network of ultra-fast, high-capacity fibre connections (often under the ocean) that link major networks across the globe. Regional ISPs connect to the backbone and provide access to end users. This layered, redundant architecture makes the Internet robust, scalable, and fault-tolerant