TCP/ IP is the basic communication language for the internet. It can be used in private networks such as the intranet and extranet. Any computer that you send a message to gets a copy of the TCP/IP. TCP/IP is a two layer protocol consisting of transmission control protocol(TCP) and the lower layer Which is Internet protocol which handles addressing so that each packet gets to its destination. TCP will be in control of managing the assembling of a message that Is being sent. IP is responsible for moving packet of data from node to node. IP forwards each packet based on a four byte destination address (the IP number). The Internet authorities assign ranges of numbers to different organizations. The organizations assign groups of their numbers to departments. IP operates on gateway machines that move data from department to organization to region and then around the world. The way that TCP/IP communicate is by using a client/server action in which the client who request and is provided a service. The communication of TCP/IP is really from one point to another meaning that it uses a point to point type of communication. Each user request is considered to be a new request, therefore TCP/IP and its higher-level applications are considered stateless. Being stateless also means that if frees network paths so that everyone can use them continuously. HTTP, Telnet, and SMTP are all associated with TCP/IP as a suite. Protocols related to TCP/IP include the User Datagram Protocol (UDP), which is used instead of TCP for special purposes. Other protocols are used by network host computers for exchanging router information. The internet is a primary reason why TCP/IP is the way It is today. The TCP/IP protocol were first developed as part of the research network ARPA. The fledgling network named ARPANET, was designed to use a number of protocols that had been adapted from existing technologies. Developers of the new network recognized that trying to use these existing protocls might eventually lead to problems as the ARPAnet scaled to a larger size and was adapted for newuses and applications. In early versions of this technology, there was only one core protocol and that was the TCP. TCP checks packets for errors and submits requests for re-transmissions if errors are found. TCP and IP were developed by a Department of Defense (DOD) research project to connect a number different networks designed by different vendors into a network of networks (the "Internet"). It was initially successful because it delivered a few basic services that everyone needs (file transfer, electronic mail, remote logon) across a very large number of client and server systems. Several computers in a small department can use TCP/IP (along with other protocols) on a single LAN. The IP component provides routing from the department to the enterprise network, then to regional networks, and finally to the global Internet. On the battlefield a communications network will sustain damage, so the DOD designed TCP/IP to be robust and automatically recover from any node or phone line failure. This design allows the construction of very large networks with less central management. However, because of the automatic recovery, network problems can go undiagnosed and uncorrected for long periods of time. There are five layers of the TCP/IP protocol suite and they are Application, Transport, Network, Network Access, and Physical. The physical network layer specifies the characteristics of the hardware applications to be used for the network. The TCP/IP transport layer ensures that packets arrive in sequence and without error, by swapping acknowledgments of the data reception. The application layer defines standard Internet services and network applications that anyone can use. The layer works with the transport layer to send and receive data. The ARPANET started with four nodes in 1969 and grew to just under 600 nodes before it was split up in 1983. The NSFNET also started with a modest number of sites in 1986. After that, the network experienced literally exponential growth. Internet growth between 1981 and 1991. TCP/IP is most commonly associated with the Unix operating system. While developed separately, they have been historically tied, as mentioned above, since 4.2BSD Unix started bundling TCP/IP protocols with the operating system. Nevertheless, TCP/IP protocols are available for all widely-used operating systems today and native TCP/IP support is provided in OS/2, OS/400, all Windows versions since Windows 9x, and all Linux and Unix variants. The TCP/IP protocols have been designed to operate over nearly any underlying local or wide area network technology. Although certain accommodations may need to be made, IP messages can be transported over all of the technologies shown in the figure, as well as numerous others. IP addresses are here to accommodate different size networks, IPv4 defines several address classes. Classes A, B, and C are used for host addressing and the only difference between the classes is the length of the NET_ID subfieldarchical for routing purposes and are subdivided into two subfields. While IP addresses are 32 bits in length, most users do not memorize the numeric addresses of the hosts to which they attach; instead, people are more comfortable with host names. Most IP hosts, then, have both a numeric IP address and a name. While this is convenient for people, however, the name must be translated back to a numeric address for routing purposes.
. In the early ARPANET, every host maintained a file called hosts that contained a list of all hosts, which included the IP address and host name). This was an adequate measure while the ARPANET was small and had a slow rate of growth, but was not a scalable solution as the network grew. UDP, described in RFC 768, provides an end-to-end datagram (connectionless) service. Some applications, such as those that involve a simple query and response, are better suited to the datagram service of UDP because there is no time lost to virtual circuit establishment and termination. UDP's primary function is to add a port number to the IP address to provide a socket for the application. The connection establishment phase comprises a three-way handshake during which time the client and server exchange their initial sequence number (ISN) and acknowledge the other host's ISN. In this example, the client starts by sending the server a TCP segment with the syn-bit set. he second part of the TCP connection is data exchange. The information here is more or less made up for example purposes only; it shows a POP server sending a banner message to the client system. The final phase is connection termination. Although TCP connections are full-duplex (even if a given application does not allow two-way simultaneous communication), the TCP protocol views the logical connection as a pair of simplex links. TCP/IP is not really a pair of communication protocols but is a suite of protocols, applications, and utilities. Increasingly, these protocols are referred to as the Internet Protocol Suite, but older name for this protocol want disappear anytime soon.

Sources: http://ccm.net/contents/292-tcp-ip https://nmap.org/book/tcpip-ref.html http://www.networkworld.com/article/2459286/why-tcp/ip-is-on-the-way-out/why-tcp/why-tcp/ip-is-on-the-way-out.html