Network Packet/Network Protocol Data Unit
A Network Packet or Network Protocol Data Unit is a formatted unit of data carried by a packet mode computer network. It consists of two kinds of data:
- Control information: It provides data needed by network to deliver the user data. For example: source and destination addresses, error detection codes like checksums, and sequencing information. Usually, control information is found in packet headers and trailers, with user data in between.
- User data: It is also known as payload.
Computer communications links that do not support packets, such as traditional point-to-point telecommunications links, simply transmit data as a series of bytes, characters, or bits alone. When data is formatted into packets, the bitrate of the communication medium can better be shared among users as compared to circuit switched networks.