What is the internet? What is a network?
Introduction
The internet is composed of a large number of interconnected networks. Data is transferred between networks through a series of "layers." Data is routed seamlessly for the end user over a series of autonomous systems, i.e. networks.
Given that the internet is a large autonomous system with no one single party controlling it, it is often referred to as a decentralized “network of networks.” For example, if a user was to visit “192.168.168.1” (assuming this local address was routable over the Internet), their Internet Service Provider (ISP) will — over the Border Gateway Protocol (BGP) — find a route to the destination network. It does this by finding the shortest path, with data often traveling through intermediary networks (through peering) until the network announcing the IP address is finally reached.
What is a Network?
A network is a series of connected devices (this can be a number of servers — even your smartphone) on a central distribution hub (router).
The illustration above shows a request from your PC to a remote server (10.0.200.2). The network 10.0.200.0/24 is being announced by network D. The ISP routes traffic to intermediate network C before being forwarded to the destination Network D.
Conclusion
In essence, a network is a series of devices such as a smartphone, home server, TV, or even your watch that are connected together through a shared hub. This shared hub then connects to an upstream network (for example, your ISP), which then connects to other networks (networks that are also connected to other networks). This is what forms the Internet.
In this series, you’ll learn more about BGP (the Border Gateway Protocol) and other networking related topics.