TCP/IP stands for Transmission Control Protocol/Internet Protocol. It’s a set of rules (protocols) that enable computers to communicate over a network like the internet.

It works by breaking down communication into layers, each responsible for a specific task.

TCP/IP is divided into 4 main layers:

• Application Layer:

  • This layer interacts directly with software applications. It decides what data needs to be sent or received.
  • Example: Web Browsing (HTTP), emails (SMTP), file transfer (FTP).
  • HOW IT WORKS:
    • A web browser sends an HTTP request for a webpage.
    • The application prepares the data and hands it to the transport layer.

• Transport Layer:

  • This layer ensures reliable delivery of data between devices.
  • Key Protocols:
    • TCP (Transmission Control protocol) : Reliable, ensures data arrives error-free, in order, and fully delivered.
    • UDP (User Datagram Protocol) : Faster but unreliable(for video streaming or gaming).
  • HOW IT WORKS:
    • Splits data into smaller chunks called segments.
    • Adds information like sequence numbers to reassemble the data on the receiver’s side.
    • Uses acknowledgments (ACKs) to confirm delivery.

• Internet Layer:

  • This layer handles addressing and routing of data packets so they reach the right destination.
  • Key Protocol :
    • IP (Internet Protocol) : Every device has an IP address that identifies it on the network.
  • HOW IT WORKS:
    • Wraps segments into packets and adds a “destination address” (like a postal address.
    • Ensures the packets are routed through different networks to reach the correct device.

• Network Access Layer:

  • This layer manages the physical transmission of data over the network hardware.
  • Key Protocol : Ethernet , Wi-Fi
  • HOW IT WORKS:
    • Converts packets into electrical signals, lights pulses, or radio waves, depending on the medium.
    • Sends the data to the next device (router, switch , etc..) in the path.

Data Flow Example: Visiting a Website

1. Application Layer:
   • Your browser sends an HTTP request for www.example.com.
2. Transport Layer:
   • TCP breaks the request into segments, ensures reliable delivery, and hands it to the Internet Layer.
3. Internet Layer:
   • IP adds the destination address (IP of www.example.com) to each packet.
   • The packets are routed across multiple networks.
4. Network Access Layer:
   • Ethernet or Wi-Fi sends the data over the physical network.

When the server responds, the process works in reverse to deliver the webpage back to your browser