Communication protocol

Machines use rules to talk.

These rules help them share things. They must agree on the rules first. This helps them work together.

Rules tell machines how to send messages. They also tell machines how to fix mistakes.

Some rules use plain text. People can read this text easily.

Other rules use a code for machines. This code is very fast. It helps machines talk quickly.

These rules are very important for the Internet.

Computers need rules to talk to each other. We call these rules a communication protocol.

Without these rules, machines would not understand each other. A protocol tells machines how to send messages. It also tells them how to fix mistakes.

To work well, devices must agree on the rules. They might use a technical standard to do this. Some rules use text that people can read. This is called a text-based protocol. Other rules use a special code for machines. We call this a binary protocol. Binary rules are very fast for computers to use.

Often, machines use a group of rules. This group is called a protocol suite. One famous suite is called TCP/IP. It helps the Internet work. Protocols use parts to send data. One part is called the header. The header holds info about the message. The other part is the payload. This part carries the actual message. Each part of the message has a specific meaning.

Have you ever wondered how two computers talk to each other? They use a system of rules called a communication protocol.

These rules allow different machines to share information without any confusion. A protocol defines the syntax, which is the structure of the messages. It also defines semantics, which means the actual meaning of the data. Rules for synchronization help devices stay in time during a conversation. Protocols also include ways to fix errors if something goes wrong.

Without these rules, digital communication would be impossible.

Working with protocols happens in a very organized way. A message is often split into two main parts. The first part is called the header. This area contains important information about how to handle the message. The second part is called the payload. The payload is where the actual message or data lives.

Sometimes, messages are too big to send all at once. If a bitstring is longer than the maximum transmission unit, it gets divided into smaller pieces. This step-by-step process ensures the data reaches its destination correctly.

People have been developing these rules for a long time. The term "protocol" was first used for data communication in April 1967. It appeared in a memo for the NPL network in the United Kingdom. Roger Scantlebury and Keith Bartlett wrote this work for Donald Davies. Later, in 1969, Bob Kahn wrote the 1822 protocol for the ARPANET. In 1970, Steve Crocker and Jon Postel developed the Network Control Program. These early steps helped build the foundation for how we connect today.

Many different groups help create these important standards. The Internet Engineering Task Force, or IETF, publishes Internet protocols. The IEEE handles rules for wired and wireless networking. Another group, the ISO, manages other types of standards. For telephone networks, the ITU-T handles the rules.

Researchers like Vint Cerf and Bob Kahn worked on the TCP design in the 1970s. By 1983, the TCP/IP suite was installed on the ARPANET. This helped create the modern Internet we use now.

Protocols can be thought of as the language of machines. Just as people use grammar to speak, computers use protocols to communicate. There are two main ways these rules are written. Text-based protocols use words that humans can easily read. Examples include FTP and early versions of HTTP. Binary protocols use a special code meant only for machines. Binary rules are very fast and use space very well. This makes them great for modern needs like HTTP/3.

A communication protocol is a formal system of rules. These rules allow two or more entities in a communications system to transmit information. Without these rules, different machines could not understand each other. Protocols define the syntax, which is the structure of the messages. They also define semantics, which is the actual meaning of the data. Furthermore, they handle synchronization to keep devices in time. They even include methods for error recovery if data is lost.

To understand how they work, think of a protocol as a language. Some experts say protocols are to communication what algorithms are to computation. In digital systems, these rules are often expressed through algorithms and data structures. When a message is sent, it is usually divided into two parts. The first part is called the header. This area contains fields relevant to the protocol's operation. The second part is the payload. This is where the actual message or data lives.

Communication often happens through a layered approach. Instead of using one single protocol, systems use a protocol suite. A protocol suite is a group of cooperating protocols. When these are implemented in software, they are called a protocol stack. Each layer in the stack handles one specific part of the problem. For example, one layer might handle application functions. Another might handle transport or network interface functions. To send a message, the system selects a protocol from each layer. It then extends the message with a protocol selector for each level.

There are two primary types of protocols based on how they represent content. The first type is the text-based protocol. These use human-readable formats like ASCII or UTF-8. They might use structured formats like XML or JSON. Text-based protocols are great for humans to inspect during debugging. Examples include FTP, SMTP, and early versions of HTTP. The second type is the binary protocol. These use all available values in a byte. They are designed for machines rather than humans. Binary protocols are very terse, which makes them fast and efficient. Modern standards like HTTP/3 use binary protocols.

History shows how these rules evolved through many brilliant minds. The term "protocol" first appeared in a 1967 memorandum for the NPL network. This was written by Roger Scantlebury and Keith Bartlett under Donald Davies. In 1969, Bob Kahn wrote the 1822 protocol for the ARPANET. Later, in 1970, Steve Crocker and Jon Postel developed the Network Control Program. This was an early example of the protocol layering concept. Louis Pouzin later designed the CYCLADES network in the early 1970s. His team implemented the end-to-end principle, making hosts responsible for reliable data delivery.

The 1970s were a busy time for protocol development. Bob Kahn and Vint Cerf worked together on the Transmission Control Program, or TCP. Cerf, Yogen Dalal, and Carl Sunshine wrote its specification in December 1974. This design was originally monolithic, meaning it was one single piece. Later, TCP was redesigned into a modular stack called TCP/IP. This modular version was installed on the ARPANET in January 1983. By 1989, a complete Internet protocol suite was developed. This laid the foundation for the modern Internet we use today.

Today, many different organizations manage these important standards. The Internet Engineering Task Force, or IETF, publishes Internet protocols. The IEEE handles rules for wired and wireless networking. The International Organization for Standardization, or ISO, manages other types. For telephone networks, the ITU-T handles telecommunications protocols. There was once a period of competition between different models. Engineers debated whether the OSI model or the Internet protocol suite was better. Eventually, the Internet protocol suite became the core component of the emerging Internet.