In TCP, a term used to describe a TCP header and its encapsulated data (also called an L4PDU). Also in TCP, the process of accepting a large chunk of data from the application layer and breaking it into smaller pieces that fit into TCP segmentsIn Ethernet, a segment is either a single Ethernet cable or a single collision domain (no matter how many cables are used).
A logical grouping of bytes that includes the network layer header and encapsulated data, but specifically does not include any headers and trailers below the network layer.
A term referring to a data link header and trailer, plus the data encapsulated between the header and trailer.

Encapsulation over WANs