Encapsulation
Once an application has generated some data encapsulation is the process of wrapping that data with headers so it can traverse through the internet to make it to it’s destination.
Layer 4 takes the data and adds the source and destination ports to the data to make it a segment.
Layer 3 takes the segment and adds a source and destination Internet Protocol (IPv4) to make it a packet.
Layer 2 takes the packet and adds a source and destination MAC address to make it a frame.
This is moved onto layer 1 to be passed along to its destination.
The reverse process is called de-encapsulation.
