How Information Is Transferred: The Packet

The basic unit of information to be transferred over the network is referred to as a packet. A packet is organized much like a conventional letter.

Each packet has a header, which corresponds to the envelope. The header contains the addresses of the recipient and the sender, plus information on how to handle the packet as it travels through each layer of the protocol suite.

The message part of the packet corresponds to the letter itself. Packets can only contain a finite number of bytes of data, depending on the network media in use. Therefore, typical communications such as email messages are sometimes split into packet fragments.