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TCP/IP, otherwise known as the Internet Protocol Suite or Transmission Control Protocol/Internet Protocol, is a collection of protocols for communications purposes deployed for the worldwide web or other networks identical to it. TCP/IP is more commonly known by its acronym form than by the "Internet Protocol Suite" moniker; the acronym contains the names of its two most important protocols, the aforementioned TCP (Transmission Control Protocol) and IP (Internet Protocol), which were the first pair of networking protocols included in this standard of sorts. Back in the sixties and seventies, a synthesis of several evolving developments—which eventually resulted in LANs or local area networks and the worldwide web at large during the eighties—led the way to modern IP networking as we know it today.
To be true, the TCP/IP was mostly a result of the research, testing, and development done by DARPA or the Defense Advanced Research Projects Agency back in the seventies. It's one of many transmission technologies DARPA began developing after pioneering and establishing the ARPANET way back in 1969. The advent of the Internet in the nineties particularly spearheaded the development of the Internet Protocol Suite. At any rate, the TCP/IP is composed of four abstraction layers—the lowest layer is the Link Layer, followed by the Internet Layer, the Transport Layer, and finally the highest layer, the Application Layer.
These TCP/IP layers determine the scope of functionality and the reach of the protocols in every layer, which is loosely implied in the names given to the layers. Each of these abstraction levels has a respective purpose and function that manages a respective set of issues connected in its scope of expertise. More to the point, the following are the basic functions and jobs of the layers enumerated earlier. The Link Layer is responsible for fundamental connectivity functions that interact with computer's network hardware, interface-to-interface message management, and all the communication technologies reserved for use by the link or the local network that the host is linked to directly.
Meanwhile, the Internet Layer—which consists of the Internet Protocol Version 6 (IPv6) that's responsible for the search and identification of network hosts, the Internet Protocol Version 4 (IPv4), and the Internet Protocol (IP) that's responsible for the definition of basic addressing namespaces—governs the methods of communication between the multitude of links that a computer has and supervises this interconnection of networks to ensure that it's streamlined throughout the entire operation. Therefore, the Internet Layer is the one that facilitates Internet interconnectivity.
Then there's the Transport Layer, which oversees direct host-to-host contact and interaction and offers an overall medium by which to deliver information between these hosts utilizing protocols such as the User Datagram Protocol (UDP) and the Transmission Control Protocol. Last but not least, the Application Layer is the highest layer because it is composed of all the protocols that define the function of the myriad of data communications services. This layer controls and organizes software-based communication on a process-to-process basis between linked Internet hosts.