The internet is a network of computers communicating through a set of protocols

The internet is a network of computers communicating through a set of protocols. Computers are physical nodes, and the connections between them constitute the internet. This communication is facilitated by protocols such as the Internet Protocol (IP), HyperText Transfer Protocol (HTTP), and Transmission Control Protocol (TCP), among others.

A network is a group of computers or other devices which are connected to eachother. For example, you at yout home might have a network of computers and devices. Their neighbor might have a similar network of devices. All these networks when connected together form the internet. The internet is a network of networks.

see The Zettelkasten is a bottom-up note-taking system

The internet is an example of a bottom-up structure because there is no top-level hierarchy. The structure is simply formed by the connections each computer has to one another