How 75,000 Independent Networks Form the Internet No One Actually Owns

The internet is not a single unified system but roughly 75,000 independent networks — including ISPs, universities, and companies like Cloudflare — that voluntarily agree to exchange traffic with each other. Unlike traditional phone networks that reserved dedicated circuits, the internet breaks data into packets, each routed independently and reassembled at the destination. This packet-switching model makes the network efficient, resilient to outages, and highly scalable, since routers only handle individual packets without tracking entire conversations. Data travelling across the internet is wrapped in four layers — application, transport, network, and link — with each layer adding addressing information on the way out and stripping it on the way back in. This modular, decentralised design, guided by the end-to-end principle, is widely credited with enabling the internet's extraordinary growth.