TCP/IP Protocol Suite Explained

Communication between 2 machines on a network are done through different protocol suits and TCP/IP is one of them.

Well Explained in this video:

tcp/ip layers

LAYER	FUNCTIONALITY
Application	Data that is sent by the user.             EX: Any script, file, form data etc.,
Transport	Data from application layer is broken down into segments. Each segment is named with sequence id so that they are received and appended in the right order in the receiver end.  The transport header is added to each segment in this layer, which is having the destination and source address with the port number.
Internet	In this layer Internet header is added to segment, which contains source and destination IP address and routing information [How to reach receiver]
Network	In this layer Network header is added to segment, which contains source and destination physical address [mac address, ethernet] In this layer Network trailer is also added to the segment, which contains error checking methods.

NOTE: Each layer adds a header and an optional trailer [Encapsulation] to the information from the preceding layer in the sender side and vice versa in the receiver side.