How Internet Work

The Internet is the backbone of the Web, the technical infrastructure that makes the Web possible. At its most basic, the Internet is a large network of computers which communicate all together.

he Internet's growth has become explosive and it seems impossible to escape the bombardment of www.com's seen constantly on television, heard on radio, and seen in magazines. Because the Internet has become such a large part of our lives, a good understanding is needed to use this new tool most effectively.

To understand How internet work first we have to know about what is internet.

Internet is a two computers need to communicate, you have to link them, either physically (Using Ethernet cable) or wirelessly (like WIFI or Bluetooth systems). All modern computers can sustain any of those connections.

Internet Address

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 address. (IP stands for Internet Protocol; more on this later.)

• So far so good. But what about connecting hundreds, thousands, billions of computers? Of course a single router can't scale that far, but, if you read carefully, we said that a router is a computer like any other, so what keeps us from connecting two routers together? Nothing, so let's do that. 
• Two routers linked together By connecting computers to routers, then routers to routers, we are able to scale infinitely. Routers linked to routers Such a network comes very close to what we call the Internet, but we're missing something. We built that network for our own purposes. 
• There are other networks out there: your friends, your neighbors, anyone can have their own network of computers. But it's not really possible to set cables up between your house and the rest of the world, so how can you handle this? Well, there are already cables linked to your house, for example, electric power and telephone. 
• The telephone infrastructure already connects your house with anyone in the world so it is the perfect wire we need. To connect our network to the telephone infrastructure, we need a special piece of equipment called a modem.
• This modem turns the information from our network into information manageable by the telephone infrastructure and vice versa.

Protocol Stacks and Packets:

If you want to send a message to a computer, you have to specify which one. Thus any computer linked to a network has a unique address that identifies it, called an "IP address" (where IP stands for Internet Protocol). 

It's an address made of a series of four numbers separated by dots, for example: 192.168.2.10. That's perfectly fine for computers, but we human beings have a hard time remembering that sort of address. To make things easier, we can alias an IP address with a human readable name called a domain name. For example (at the time of writing; IP addresses can change) google.com is the domain name used on top of the IP address 142.250.190.78. So using the domain name is the easiest way for us to reach a computer over the Internet.

Therefore the message 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 a protocol stack. Every computer needs one to communicate on the Internet and it is usually built into the computer's operating system (i.e. Windows, Unix, etc.). The protocol stack used on the Internet is refered to as the TCP/IP protocol stack because of the two major communication protocols used.

Networking Infrastructure

The ISP maintains a pool of modems for their dial-in customers. This is managed by some form of computer (usually a dedicated one) which controls data flow from the modem pool to a backbone or dedicated line router. This setup may be refered to as a port server, as it 'serves' access to the network. Billing and usage information is usually collected here as well.

After your packets traverse the phone network and your ISP's local equipment, they are routed onto the ISP's backbone or a backbone the ISP buys bandwidth from. From here the packets will usually journey through several routers and over several backbones, dedicated lines, and other networks until they find their destination.

As you might notice, when we browse the Web with a Web browser, we usually use the domain name to reach a website. Does that mean the Internet and the Web are the same thing? It's not that simple. As we saw, the Internet is a technical infrastructure which allows billions of computers to be connected all together. Among those computers, some computers (called Web servers) can send messages intelligible to web browsers.