The etymology of the word is various, it was used for hundreds of years. From Middle French prothocole (c. 1200, Modern French protocole), from Medieval Latin protocollum "draft," literally "the first sheet of a volume" (with contents and errata), from Greek protokollon "first sheet glued onto a manuscript," where protos is "first" and kolla is "glue."
In modern day computer technology protocol is a set of rules and guidelines for communication between two or more computers. Successful transmission of data over the network depends on how networks follow these rules.
At different levels of telecommunication connection different protocols apply. Some protocols are used at the device level, some - at the software program level. OSI (Open Systems Interconnection) makes an effort to standardize protocols, and according to it protocols are present at each layer of telecommunication exchange, and both sides of communication should recognize and observe these protocols. One can often read about protocols as an industry or international standard.
While OSI was working on its networking standards, TCP/IP protocol became widespread on multi-vendor networks for internetworking.
The TCP/IP Internet protocols consist of:
- Transmission Control Protocol (TCP protocol). It is currently considered to be the basic communication language on the Internet that can also be used for private network communication. At an intermediate level this protocol offers communication for an application and the Internet Protocol. The app does not necessarily need to know the mechanisms for sending data via a link to another host. At the transport layer, TCP protocol handles handshaking, transmission, and abstraction of the network connection to the app.
- Internet Protocol (IP protocol). This protocol works according to a set of rules for sending and receiving messages at the Internet address level, when the data is sent from one computer to another over Internet. Each computer on the network has a unique identifier - an IP address.
- Other popular protocols include Hypertext Transfer Protocol (HTTP) and File Transfer Protocol (FTP). The Hypertext Transfer Protocol (HTTP) is the base for data communication over the Internet, and FTP is a File Transfer Protocol, which speaks for itself.
We only mentioned the most common and foundational protocols. There are many more out there serving different purposes.
Thanks to the protocols apps and devices can communicate despite the distance. For example you can access USB or COM port devices over TCP/IP network and use them as if they were right here and not oceans away. USB Network Gate is an ultimate USB over TCP/IP solution, while a great way to share and access Serial over IP is Serial to Ethernet Connector.