Internet – Explained

How internet works?  Though we use this service regularly, we are not much conversant about what happens exactly inside when we request for a web page by typing an address in the browser or while sending an email.  Here is a brief know how.

Because the Internet is a global network of computers each computer connected to the Internet must have a unique address. Internet addresses are in the form nnn.nnn.nnn.nnn where nnn must be a number from 0 – 255. This address is known as an IP (Internet Protocol) address.

The picture below illustrates two computers connected to the Internet; your computer with IP address and another computer with IP address The Internet is represented as an abstract object in-between.

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If you connect to the Internet through an Internet Service Provider (ISP), you are usually assigned a temporary IP address for the duration of one time connection with ISP.

So your computer is connected to the Internet and has a unique address. How does it ‘talk’ to other computers connected to the Internet? An example should serve here: Let’s say your IP address is and you want to send a message to the computer


The message you want to send is “Hello computer!”. Obviously, the message must be transmitted over whatever kind of wire connects your computer to the Internet. Let’s say you are connected to your internet service provider through broadband modem from home and the data you want to send or receive must be transmitted over the phone line. Therefore the data  must be translated from alphabetic text into electronic signals, transmitted over the Internet, then translated back into alphabetic text. How is this accomplished?   Through the use of TCP/IP Protocol. If minute details are omitted, explaining of TCP/IP would be simpler. It’s a common procedure that both the computer use to send or receive data it.

If we were to follow the path that the message “Hello computer!” took from our computer to the computer with IP address, it would happen something like this through TCP/IP Protocol.

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  • The message would start at the top of the protocol stack on your computer and work it’s way downward.
  • If the message to be sent is long, each stack layer that the message passes through may break the message up into smaller chunks of data. This is because data sent over the Internet (and most computer networks) are sent in manageable chunks. On the Internet, these chunks of data are known as packets.
  • The application layer is nothing but Protocol (or procedure) specific to applications such as WWW, e-mail, File transfer protocol etc., that we use while using internet. The packets would go through the Application Layer and continue to the TCP layer where each packet is assigned a port number. Ports are unique numbers used by a particular program and as you know many programs may be using the TCP/IP stack and sending or receiving messages in a particular computer in a particular time. We need to know which program on the destination computer needs to receive the message because it will be listening on a specific port. After going through the TCP layer, the packets proceed to the IP layer. This is where each packet receives it’s destination address,
  • Now that our message packets have a port number and an IP address, they are ready to be sent over the Internet. The hardware layer takes care of turning our packets containing the alphabetic text of our message into electronic signals and transmitting them over the phone line.
  • On the other end of the phone line your ISP has a direct connection to the Internet. The ISPs router examines the destination address in each packet and determines where to send it. Often, the packet’s next stop is another router. More on routers and Internet infrastructure later.
  • Eventually, the packets reach computer Here, the packets start at the bottom of the destination computer’s TCP/IP stack and work upwards.
  • As the packets go upwards through the stack, all routing data that the sending computer’s stack added (such as IP address and port number) is stripped from the packets.
  • When the data reaches the top of the stack, the packets have been re-assembled into their original form, “Hello computer!”

How packets travel ?

This amazing video will explain the journey of packets from one computer to the other.  Listen carefully, data that broken into different kinds of packets such as TCP packet, UDP packet etc and the equipments such as router, switch etc that are used to transmit these packets have been animated as different characters and named as warriors in this short film.  After watching this video you will have an idea about the complexity in transmission of data over internet.  And it’s also sure that you won’t complain anymore while your connection is slow.

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