How the Internet Works

The Internet is a global system of interconnected computer networks. Rather than a single central service, it relies on thousands of autonomous systems (AS) operated by ISPs, universities, tech companies, and governments that peer with each other to route traffic.

Physical fiber optic cables laid under the ocean floor, along railways, and through metropolitan pipes form the core internet transit lines, carrying terabits of multiplexed light pulses across continents.

Data is not sent as a single block; it is broken down into small units called packets. Every packet contains a header specifying its source IP address, destination IP address, protocol type, and sequence number.

Routers at the edge and core of the network inspect these destination addresses and use dynamic routing tables (via protocols like BGP) to determine the next hop. If one path becomes congested or severed, packets are dynamically rerouted through alternative nodes.

Because packets can take different paths through the network, they may arrive out of order. Transport layer protocols like TCP ensure that all packets are acknowledged, retransmitted if lost, and reassembled in the correct order before being delivered to the application.