What Is Transmission Control Protocol


TCP (Transmission Control Protocol) is a standard that defines how to establish and maintain a network conversation through which application programs can exchange data. TCP works with the Internet Protocol (IP), which defines how computers send packets of data to each other.

The Transmission Control Protocol is one of the main protocols of the Internet protocol suite. It originated in the initial network implementation in which it complemented the Internet Protocol. Therefore, the entire suite is commonly referred to as TCP/IP.

protocol is a standard set of rules that allow electronic devices to communicate with each other. These rules include what type of data may be transmitted, what commands are used to send and receive data, and how data transfers are confirmed


In the world of technology, there are vast numbers of users’ communicating with different devices in different languages. That also includes many ways in which they transmit data along with the different software they implement. So, communicating worldwide will not be possible if there were no fixed ‘standards’ that will govern the way user communicates for data as well as the way our devices treat those data. Here we will be discussing these standard set of rules.

Yes, we’re talking about “protocols” which are set of rules that help in governing the way a particular technology will function for communication. In other words, it can be said that the protocols are digital languages implemented in the form of networking algorithms. There are different networks and network protocols, user’s use while surfing.

  1. Transmission Control Protocol (TCP): TCP is a popular communication protocol which is used for communicating over a network. It divides any message into series of packets that are sent from source to destination and there it gets reassembled at the destination.
  2. Internet Protocol (IP): IP is designed explicitly as addressing protocol. It is mostly used with TCP. The IP addresses in packets help in routing them through different nodes in a network until it reaches the destination system. TCP/IP is the most popular protocol connecting the networks.
  3. User Datagram Protocol (UDP): UDP is a substitute communication protocol to Transmission Control Protocol implemented primarily for creating loss-tolerating and low-latency linking between different applications.
  4. Post office Protocol (POP): POP3 is designed for receiving incoming E-mails.
  5. Simple mail transport Protocol (SMTP): SMTP is designed to send and distribute outgoing E-Mail.
  6. File Transfer Protocol (FTP): FTP allows users to transfer files from one machine to another. Types of files may include program files, multimedia files, text files, and documents, etc.
  7. Hyper Text Transfer Protocol (HTTP): HTTP is designed for transferring a hypertext among two or more systems. HTML tags are used for creating links. These links may be in any form like text or images. HTTP is designed on Client-server principles which allow a client system for establishing a connection with the server machine for making a request. The server acknowledges the request initiated by the client and responds accordingly.
  8. Hyper Text Transfer Protocol Secure (HTTPS): HTTPS is abbreviated as Hyper Text Transfer Protocol Secure is a standard protocol to secure the communication among two computers one using the browser and other fetching data from web server. HTTP is used for transferring data between the client browser (request) and the web server (response) in the hypertext format, same in case of HTTPS except that the transferring of data is done in an encrypted format. So it can be said that https thwart hackers from interpretation or modification of data throughout the transfer of packets.
  9. Telnet: Telnet is a set of rules designed for connecting one system with another. The connecting process here is termed as remote login. The system which requests for connection is the local computer, and the system which accepts the connection is the remote computer.
  10. Gopher: Gopher is a collection of rules implemented for searching, retrieving as well as displaying documents from isolated sites. Gopher also works on the client/server principle.

What TCP is used for

TCP is used for organizing data in a way that ensures the secure transmission between the server and client. It guarantees the integrity of data sent over the network, regardless of the amount. For this reason, it is used to transmit data from other higher-level protocols that require all transmitted data to arrive. Examples include:

  • Secure Shell (SSH) File Transfer Protocol (FTP) Telnet For peer-to-peer file sharing, and, in Telnet’s case, logging into another user’s computer to access a file.
  • Simple Mail Transfer Protocol (SMTP) Post Office Protocol (POP) Internet Message Access Protocol (IMAP) For sending and receiving email
  • HTTP: For web access

These examples all exist at the application layer of the TCP/IP stack  and send data downwards to TCP on the transport layer.

Characteristics of Transmission Control Protocol (TCP).

Stream Data transfer : Applications working at the Application Layer transfers a contiguous stream of bytes to the bottom layers. It is the duty of TCP to pack this byte stream to packets, known as TCP Segment, which are passed to the IP layer for transmission to the destination device. The application does not have to bother to chop the byte stream data packets.

Reliability : The most important feature of TCP is reliable data delivery. In order to provide reliability, TCP must recover from data that is damaged, lost, duplicated, or delivered out of order by the Network Layer. TCP assigns a sequence number to each byte transmitted, and expects a positive ackknwledgement from the receiving TCP layer. If the ACK is not received within a timeout interval, the data is retransmitted. The receiving TCP uses the sequence numbers to rearrange the TCP segments when they arrive out of order, and to eliminate duplicate TCP segments.lFlow control : Network devices operate at different data rates because of various factors like CPU and available bandwidth. It may happen a sending device to send data at a much faster rate than the receiver can handle. TCP uses a sliding window  mechanism for implementing flow control. The number assigned to a segment is called the sequence number and this numbering is actually done at the byte level. The TCP at the receiving device, when sending an ACK  back to the sender, also indicates to the TCP at the sending device, the number of bytes it can receive (beyond the last received TCP Segment without causing serious problems in its internal buffers.

Multiplexing : Multitasking achieved through the use of port numbers.

Connections : Before application processes can send data by using TCP, the devices must establish a connection. The connections are made between the port numbers of the sender and the receiver devices. A TCP connection identifies the end points involved in the connection. A socket number is a combination of IP Address and port number, which can uniquely identify a connection.

Full duplex : TCP provides for concurrent data streams in both directions

You have learned the characteristics of Transmission Control Protocol (TCP). Click “Next” to continue.

Importance of TCP

TCP is important because it establishes the rules and standard procedures for the way information is communicated over the internet. It is the foundation for the internet as it exists today and ensures that data transmission is carried out uniformly, regardless of the location, hardware or software involved. For this reason, it is flexible and highly scalable, meaning new protocols can be introduced to it and it will accommodate them. It is also nonproprietary, meaning no one person or company owns it.

The most important features can be summarized as follows: TCP is connection-oriented and enables two-way communication between two endpoints after the three-way handshake. TCP is reliable because the protocol ensures that all data is fully transmitted and can be assembled by the receiver in the correct order

Transmission Control Protocol (TCP) – a connection-oriented communications protocol that facilitates the exchange of messages between computing devices in a network. It is the most common protocol in networks that use the Internet Protocol (IP); together they are sometimes referred to as TCP/IP.

TCP is used for organizing data in a way that ensures the secure transmission between the server and client. It guarantees the integrity of data sent over the network, regardless of the amount. For this reason, it is used to transmit data from other higher-level protocols that require all transmitted data to arrive.

What layer is Transmission Control Protocol

?transport layer

The Transmission Control Protocol (TCP) is a transport layer protocol, and the Internet Protocol (IP) is a network layer protocol.

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