What is TCP/IP? [A Complete Overview]

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TCP/IP is a set of rules used to connect two devices in a network. For instance, let’s say two computers want to communicate with each other, the first one using ASCII encoding and the second one using Unicode encoding. As they are using two different encoding systems, communication may not be possible. So they need some rules describing how a message will be converted or interpreted by a computer. These rules are called internet protocols. TCP/IP is a set of those protocols which I will explain in detail in this article.

What is TCP/IP?

TCP and IP stand for Transmission Control Protocol and Internet Protocol respectively. TCP and IP both are part of the Internet protocol suite. The Internet protocol suite was developed by the US Department of Defense’s Advanced Research Projects Agency (ARPA) for ARPANET in the 1970s and became publicly accessible in the 1980s. TCP divides data into smaller packets, then those packets are transmitted from the sender to the receiver. At the receiver end, TCP helps to rearrange the data. And, the IP is responsible for addressing and routing data packets on a network. This is how TCP and IP work together to make communication happen.

Characteristics of TCP/IP

Here are some of the characteristics of the TCP/IP suite:

  • Layered Architecture: It has different layers and each layer has specific functionality.
  • Addressing: It uses IP addresses to identify the route of the packets.
  • Packet Switching: It uses packet switching to transfer data. Firstly, it divides data into small packets sends them over the internet, and then assembles them at the destination.
  • Multiplexing: Multiplexing allows multiple applications to use the same connection. They use different ports for this.
  • Reliability: TCP/IP transfers data reliably with no data loss.

How Does TCP/IP Work?

When a computer sends a message to another computer, this is what happens in the background:

  1. TCP breaks the message into small data packets. Each packet has its own TCP header. TCP header contains information like sequence number, checksum (detect errors or corruption in data) and other metadata.
  2. Then IP encapsulates each packet in an IP header. The IP header contains the IP address of the source and destination.
  3. Next, the data packets are routed based on the IP address of their destination.
  4. When those packets arrive at the other computer, IP extracts the IP header and sends them to TCP.
  5. The TCP reassembles the packets based on the sequence number and checks for errors.

The following image provides a visual representation of how TCP/IP works:Visual representation of what is TCP/IP and how it works

Four Layers of TCP/IP

There are four layers of protocols in the TCP/IP protocol suite. Here I will explain them to you:

  1. Application Layer: This layer contains those protocols different services use. For instance, HTTP(Hypertext Transfer Protocol) for web serving, SMTP(Simple Mail Transfer Protocol) for emailing, and FTP(File Transfer Protocol) for file sharing.
  2. Transport Layer: It is the TCP layer. It delivers data reliably and efficiently. This layer breaks data into small data packets.
  3. Internet Layer: It is the IP layer. This layer is responsible for routing the data packets. This layer will encapsulate the data packets which contain the IP addresses of the source and destination.
  4. Network Interface Layer: This layer contains those protocols which are responsible for transmitting data on the internet. Ethernet and Wi-Fi are examples of the network interface layer.

Some Protocols of the TCP/IP Suite

Here I have listed some of the protocols that are the part of TCP/IP suite below:

  • Transmission Control Protocol (TCP): Delivers data reliably between different hosts on a network.
  • Internet Protocol (IP): Responsible for addressing and routing.
  • User Datagram Protocol (UDP): Applications that can tolerate losing data use this protocol.
  • SSH (Secure Shell): Provides secure remote access to a computer or server over an insecure network.
  • File Transfer Protocol (FTP): Provides a standard way to transfer files.
  • Hypertext Transfer Protocol (HTTP): It is used to access websites and web applications.
  • Simple Mail Transfer Protocol (SMTP): Hosts use this protocol to send emails.
  • Telnet: It also provides remote access to a computer or server, but less securely.
  • Domain Name System (DNS): Resolves domain names to IP addresses.
  • Dynamic Host Configuration Protocol (DHCP): Automatically assigns IP addresses to hosts on a network.

Advantages and Disadvantages of TCP/IP

The TCP/IP is used widely because of some advantages. However, it has some limitations. That is why there are some advanced protocols to overcome the limitations.


  • Compatible: TCP/IP is a versatile and reliable protocol suite as a wide range of hardware and software supports this protocol.
  • Publicly Available: Anyone can use and implement the TCP/IP.
  • Scalable: TCP/IP can handle a large number of devices and networks which makes it ideal for communication over the Internet.
  • Reliable: It transfers data to its destination with 100% certainty.
  • Secure: TCP/IP includes a lot of security protocols to ensure a secure transfer of data.


  • Complex: TCP/IP is a complex model to set up and manage.
  • Vulnerable: Even though TCP/IP has some security protocols, it is vulnerable to DoS attacks.
  • Irreplaceable: TCP/IP protocols are hard to replace.
  • Uncertainty in Quality: It ensures data will reach its destination but it doesn’t ensure the quality of the data.
  • Conceptual Unclarity: It doesn’t provide clear concepts of services, interfaces, and protocols. That’s why it is hard to describe it in new technology.


TCP/IP is extremely important for networking. In this article, I have tried my best to give you an overview of TCP/IP.  I hope this article has been helpful to you.

Frequently Asked Questions

What does TCP IP mean?

TCP/IP means Transmission Control Protocol/Internet protocol. These protocols are the set of rules that enable a computer to establish a connection over a network or internet which facilitates data delivery.

What are the 4 layers of TCP model?

There are 4 layers of the TCP model:

  1. Application Layer.
  2. Transport Layer.
  3. Internet Layer.
  4. Network Interface Layer.

What is TCP vs UDP?

TCP stands for transmission control protocol, while UDP stands for user datagram protocol. Prior to data exchange, TCP creates a bi-directional connection; UDP, on the other hand, views each packet as a separate entity. Furthermore, UDP sends data in an unordered manner and lacks error-checking, whereas TCP provides the capacity to control the flow of data delivery and error-checking.

How does TCP work?

TCP facilitates communication between applications or devices over a network. It first breaks the data into small packets. Each packet has its own TCP header that contains information like sequence number, checksum, and other metadata. Then IP encapsulates each packet in an IP header containing the IP address of the source and destination. Next, the data packets are routed based on the IP address of their destination. When those packets arrive at the other computer, IP extracts the IP header and sends them to TCP. The TCP reassembles the packets based on the sequence number and checks for errors.

What is TCP header?

Every data packet transmitted over TCP contains a header of 10 mandatory fields total of 20 bytes. Each TCP header carries detailed information about the connection and the current data being sent.

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Walid Al Asad

Hello Everyone! I am Walid Al Asad. Currently, I am working at a tech company named Softeko as a Linux Content Developer Executive. I live in Dhaka, Bangladesh. I have completed my BSc. in Mechanical Engineering from Bangladesh University of Engineering and Technology (BUET). You can find me on LinkedIn, and ResearchGate. Read Full Bio

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