What is a Data Packet?

Robert J. Ditzig
NetworkingFundamentals

A data packet is the basic logical unit of information transferred in data communications. It consists of a certain number of data bytes wrapped or encapsulated in headers and/or trailers that contain information about where the packet came from, where it's going, and other relevant details. Different protocols add their own layers of header information to the packet, which are then interpreted by the corresponding protocols in receiving devices. The term "packet" is commonly used in networking to refer to these units of data transmission.

The data at each layer of the OSI model is referred to by different names:

  • Layer 7 (Application layer): Data is referred to as data.
  • Layer 6 (Presentation layer): Data is referred to as data.
  • Layer 5 (Session layer): Data is referred to as a message.
  • Layer 4 (Transport layer): Data is referred to as a segment.
  • Layer 3 (Network layer): Data is referred to as a datagram.
  • Layer 2 (Data Link layer): Data is referred to as a frame.
  • Layer 1 (Physical layer): Data is transmitted as individual bits.