TCP/IP


The Internet protocol suite is the computer networking model and set of communications protocols used on the 
Internet and similar computer networks. It is commonly known as TCP/IP, because its most important protocols,
the Transmission Control Protocol (TCP) and the Internet Protocol (IP) were the first networking protocols defined
in this standard. It is occasionally known as the DoD model, because the development of the networking model was 
funded by DARPA, an agency of the United States Department of Defense.

TCP/IP provides end-to-end connectivity specifying how data should be packetized, addressed, transmitted, routed
and received at the destination.
This functionality is organized into four abstraction layers which are used to sort all related protocols according
 to the scope of networking involved.
From lowest to highest, the layers are 
  
the link layer
, containing communication methods for data that remains within a single network segment (link);
the internet layer
, connecting independent networks, thus establishing internetworking;
the transport layer
handling host-to-host communication;
and the application layer
, which provides process-to-process data exchange for application.
TCP/IP
x