What is meant by data encapsulation?

Data encapsulation is the process of adding a header to wrap data as it flows down the OSI model, this is done to add additional information required to process the data as it moves from source to destination.

Encapsulation begins at layer 4 of the OSI as the Transport layer converts the data into segments. Here the header contains port numbers of source and destination.

When the segments are converted into packets, at the network layer, another header is added containing the IP addresses of both source and destination.

The data link layer adds another header containing the source and destination MAC addresses. It also adds a trailer which contains a frame check sequence that is used to verify the data on receipt.