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What is the internet? How does the Internet work?
When you chat with someone on the Internet or send an email, have you ever think about how many different computers are working together to complete these tasks? You are sitting on the table in front of your PC or on the laptop and on the other side, your friend is ready to contact you with his computer. But there are a dozen computers in the gap between your friends and you. In this way, millions of computer are connected to each other across the world make a web or net is called the Internet. But how this computer able to establish relationships within themselves? Let's visit all these things from near and dear ones.

What is the Internet?
Global communication has become much better now and all of these achievements are for the Internet. In less than 20 years it has spread to approximately 210 different countries. Even the poor countries of the world have become connected to this net.
Most of you, including me, think that the word internet means going online. The truth is that this is nothing but a common computer network. It is just like a road that wraps around the world. Just as the traffic flows through the road to its destination, the data reaches by various computers and arrives at its destination. Consistently that's the main foundation of the Internet. The Internet is actually a system of connecting different computers together (computers in your home, office, school ).
One computer is connected to another computer in different ways. Some are connected by the old copper cable some may be by fiber-optic cable (which sends the data between the vibrations of the light) again, some are connected to the wireless connection (connected through radio waves ) or some are connected to the satellite. And this is how we can enjoy instant messaging, email service, or download mp3 music files.

What is the real work of the internet?
The functions of the Internet is actually very easy, it only transmits data from one place to another. The main functions of the machines that have been integrated into the Internet are data transfer and distribution. To compare the reality, the internet can be compared to the Postal Service. In postal service, letters are transmitted from one place to another. But it does not matter where the letter came from or what is written in the letter. Even there is not a headache if the letter is empty. Its work only reaches the letter to their destination. The Internet works the same way.
Internet service also holds much information from one place to another such as Postal Service. So, if the data is transmitted, then the internet will complete it.Whether you sent an email or sent a message, Internet has no interest in it. However, the Internet will only help to complete the process of transferring the data. Now we are finding new uses of the internet based on the data transfer method. For example, when two European investors created Skype, they brought the phone call over the net. They created a program where our words converted into data and continue communication by exchange the data through internet. But it was not possible to create a separate internet for Skype for sharing our talk directly.

How are internet data transmitted?
The Internet works largely like a telephone network. But there is a difference between a call on telephone lines and carry data through the Internet. When you ring a friend, a direct connection (or circuit) is established between you and your friend in a telephone line. As long as you are connected to the telephone, the circuit will open. Circuit switching is the method where two telephones are connected to each other. The electronic telephone exchange system controls who will be heard and who will be sent.
Thinking a little more, you can understand that circuit switching is a really inefficient method for setting up a network. Whenever you are connected to your friend on the phone, you will not be able to associate with anyone else. (Think, you're typing an email, which may take an hour or more, then what will happen if nobody can send an email to you?) Moreover, if you bring coffee mugs putting your phone on, you are not sending any information, your phone will be connected to your friend's phone. You are charging for every second and nobody can call you at this time. So circuit switching can never be an ideal network. What kind of network is used to carry data on the internet?

Packet switching
Sometimes the Internet uses the circuits switching method to carry its data. For example, if you use Dial-Up Connection (where your computer dials a telephone number to reach your Internet provider, and it works like a normal phone call) to connect the Internet. Here you use the circuit switching method to come online. So no one can call you till you connected. And you have to pay for every second to stay connected. Instead of going fast, your net connection will work at the turtle speed.
But most of the internet data is carried out in a whole new method called Packet Switching. Imagine that you want to send an email to any of your USA friends. So here's you do not have to be connected directly for getting this mail completely. After sending your mail to packet switching, it divides into several parts. And each of these parts is called packets. Each packet is tagged for where it has to go and they can travel to its destination in differents way. When the fragments reach their destination they merge again and appear as a mail.
Packet switching method is more feasible than circuit switching method. You don't need to be connected constantly. Even you're not putting off the line. Anybody can use the same line at the same time. Therefore the specific packets will reach your address exactly. Since packets reach different routes, there is no chance of obstruction. As a result, you may observe a very fast speed.

How Packet Switching works?
Before understanding how packet switching works, you need to perceive how circuit switching works. Suppose you live in the USA and plan to come to the UK. Suppose you are thinking of picking up your building, LOL! What do you have to do?
First, you have to see a road to travel easily. Then you'll need some trucks. Also, need a special ship to cross the sea. It is much difficult to get the whole thing and takes lots of time to reach the destination. Moreover, if someone tries to come to the same root, he will also get stuck. Actually, the circuit switching method works the same way. Hereafter this method is called a telephone call. Now Imagine that you broke down your building in parts and numbered each brick. Each brick stuffed the envelope and sent it different roots to your destination. Few by the ship, few by air or roads. Then built your previous building by adding them according to their number. Since the bricks have traveled with different roads, no street jam will create. Furthermore, others can use the same road at the same time.
Packet switching works in this way. When you email or browse a site with a browser, all the data is divided into many packets and spreads over the Internet.

How do computers work for internet?
There are hundreds of millions of computers across the internet. But not every computer does the same thing. Some of these computers only collect information and send them from where it is requested. Hereafter these machines are called servers. The machines or computers that store any documents are called file servers. The servers that contain and process your mail are called mail servers. As well as the servers that contain webpages are called web servers. There are several servers on the internet.
The computers that collect data from the server are called client computers. When you check mail on your computer, your computer works as a client, your ISP (Internet Service Provider) works as a server and the mail you check comes from a mail server. So its go without saying that the number of clients on the internet is more than the number of servers, almost a billion.
When two computers are connected with each other, it is called Peers. If you message or share photos with your friend, this is peer-to-peer (P2P) communication. In P2P communication your computer behaves like a client and a server as well. Suppose you have sent a photo to your friend, then your computer works as a server (sent photos) simultaneously your friend's computer will work as a client (access photos).In the same way, once your friend sends a photo, his computer works as a server (photo sets) and your computer as a client (access photos).
Apart from the server and client, there is a middle computer which is another part of the internet. It's nothing but the Router. It only helps to connect different systems. If there is more than one computer in your home or school or office, then the router helps connect everyone to the Internet.

What is TCP / IP (DNS) and DNS?
Sharing data on the Internet is not like to carry any the brick within the envelope at all. It is not possible to control those data by any person. Numerous data transmissions through the net every day - approximately 3 billion emails and lots of traffic are download and upload by 250 million websites around the world. Now the question is, if all data are converted into packets and sent them without any control, how can they reach the original destination without any problem?
The answer is TCP / IP (TCP / IP) or Transmission Control Protocol / Internet Protocol. This system only helps to deliver all packets to its destination. It's just like two in one system. In the computer world, "protocol" means a standard which ensures to reach everything to its destination. Now the question arises in your mind that what does TCP / IP actually work? Let's try to understand. Internet Protocol or IP is a simple addressing system. All the machines on the Internet, I have a different IP address. When every machine has a separate IP, it is easy to find out them and it is possible to send those packets accordingly. IP addresses are basically some pattern of numbers. And the numbers are separated by using dot, commas or colons. Such as 12.34.56.78 or 123.255.212.55 or 123a:b716:7291:0da2:912c:0321:0ffe:1da2.

For More about IP address read this post. WHAT IS IP ADDRESS? | IPV4 AND IPV6

Another part of this control system is the Transmission Control Protocol (TCP). This system determines how to send packets from one IP to another. And this system brings together all packets. Besides, if a packet is lost when sending, it re-sent those packet again.

I try to present this topic as much as simple. I don't if I could. If you have any question, let me comment below and share the post.