In the world of IT, packet or packets is the term used to describe a unit of data, such as bytes or characters. When sending data over a network, messages or files are broken down into manageable packets before transmission. These packets can also be referred to as a datagram, a segment, a block, a cell or a frame, depending on the protocol used to break it down. Once they have been transmitted, the packets are re-assembled at the receiving end to create the original data file.
The structure of a packet can vary depending on which protocol is used to format it. Typically a packet consists of a header and a payload. The header carries information regarding the reassembly of the packets e.g. where they came from, where they are going to and in what order. The payload refers to the data that it carries.