Answer:
Encapsulation
Step-by-step explanation:
There are seven layers in the OSI network model. These layers are, application, presentation, session, transport, network, data-link and physical layer.
Each layer of the OSI model has a PDU or protocol data unit. These PDUs are form by encapsulation.
The application, presentation and session data. When it moves to the transport layer, it is encapsulated within the transport header. This new pdu is called segment.
This process continues in network and data-link to give packet and frame PDUs respectively.