The transmission control protocol is one of the two protocols that make up the Internet connection suite. This protocol is combined with the Internet protocol to form the foundation of nearly all Internet traffic. These protocols are almost inseparable in use, relying completely on each other for proper functioning; as a result, the Internet connection suite is typically abbreviated as TCP/IP (transmission control protocol/Internet protocol). The transmission control protocol is responsible for the disassembling and reassembling of data, and the Internet protocol handles the routing and transmission.
Internet traffic is primarily made of up of small data bursts called packets. These packets contain information relating to the origin and destination of the data as well as some optional additional information. The packets are created and reassembled by the transmission control protocol and sent over the Internet by the Internet protocol.
To illustrate this process, say a document is moved from a remote computer to a local one. The computer receives the move command, and the Internet protocol determines how the document needs to move between the computers. The Internet protocol then asks the transmission control protocol to split the document up in a specific way. The TCP then divides up the document into packets, and the Internet protocol sends them out.
When the document packets arrive at the local computer, the TCP begins to reassemble them. It first checks to see if it has all of them and if they are in proper shape—if it needs replacements, it submits a request for the parts it needs and waits for them to arrive. After it gets all of the pieces, it reorders them in the proper sequence and assembles the document. It then sends it on to the Internet protocol, which informs the computer that the file has arrived.
These processes make up the vast majority of Internet usage. Programs like web browsers, email clients and file transfer systems use this basic back and forth process for every interaction. This unified system allows unrelated programs and systems to send information to one another without conversion. It is immaterial what operating system or program sent the information, as the control protocol actually did the work.
Since this is the basic cornerstone of the Internet, the protocol never changes very much. This allows systems backward compatibility over the Internet. Changes in protocols would cause older machines to permanently disconnect. Even without a common update, the system is so simple that it rarely requires any additional monitoring or attention.