While the seven-layer OSI model serves as a foundational teaching reference, practical Internet communication relies on the simpler TCP/IP model. The TCP/IP model condenses network operations into four functional layers: Link, Internet, Transport, and Application.

Data moves through these layers via a process called encapsulation:

• Sending Data (Encapsulation): As data travels down the protocol stack on the sending device, each layer wraps the payload with its own specialized header containing routing and protocol instructions.
• Receiving Data (Decapsulation): When data arrives at the destination device, it travels back up the stack. Each layer reads and removes its corresponding header before passing the remaining data payload to the layer above it.