TCP/IP Defined - Overview of TCP/IP


What Is TCP/IP?

TCP/IP, an abbreviation for Transmission Control Protocol/Internet Protocol, refers to a suite of protocols created especially to connect dissimilar computer systems. TCP/IP provides a common set of communications rules (or protocols) for all interconnected computer systems to follow. Computer systems that are connected with TCP/IP form a network called an internet.



TCP/IP evolved as the result of research funded in the 1970s by the Defense Advanced Research Projects Agency (DARPA), an agency of the U. S. Department of Defense (DoD). The need to connect computer systems using different hardware, operating systems, and network technologies was becoming increasingly important to the military, and the DoD recognized that addressing the interoperability problem would be critical in the future.

TCP/IP was first implemented in the ARPANET, a packet-switching network that provided communications between government agencies and military facilities as well as some defense contractors and universities. ARPANET served as the backbone for DARPA's TCP/IP research, which proved so successful that in 1983 the Office of the Secretary of Defense designated TCP/IP a networking standard.


What Is an Internet?

An internet is a group of computers that are linked to each other. You can use the generic term internet — with a lowercase “i” — to describe computer systems connected by TCP/IP. When capitalized — as in Internet — it refers to the world-wide network that connects thousands of major research institutions, universities, corporations, and government laboratories. Members of the Internet share data and resources across the network. Some of the organizations that belong to the Internet include:

  • Thousands of new commercial sites
  • Almost all colleges and universities worldwide
  • The National Science Foundation (NSF)
  • The Department of Energy (DoE)
  • The National Aeronautics and Space Administration (NASA)
  • Major online services


Independent Internets

TCP/IP is often used to create internets that are independent of the global Internet. Diverse industries such as telecommunications, health care, and agriculture widely use TCP/IP. It can benefit any organization that wants to:

  • Connect dissimilar systems (for example, connect an OpenVMS system to a UNIX system).
  • Connect hosts at different facilities that span large geographical distances.
  • Connect local or wide area networks.
  • Connect a host or network to the Internet.


Virtual Network

An internet is also referred to as a virtual network. This is because it allows your local host to communicate with other connected remote hosts as if all hosts were connected to the same local network.