To manage complexity, networking tasks are partitioned into hierarchical layers where each layer performs a specific job and relies on the layer beneath it. The standard educational model is the seven-layer OSI model: Physical (cables, radio waves, voltages), Data Link (communication between directly connected devices), Network (packet routing across multiple networks), Transport (end-to-end delivery between applications), Session (conversation management), Presentation (formatting and encryption), and Application (user-facing software).

In practical operation, the Internet uses the simpler four-layer TCP/IP model: Link, Internet, Transport, and Application. Data movement across these layers relies on encapsulation: as data descends through the layers on a sending device, each layer wraps the payload with its own header. Upon arrival at the receiving device, the data moves back up through the stack, and each header is stripped away in turn.