The Internet itself provides many good websites which describe the history and all technical issues of the Internet more precisely than this section which is designed for beginners to give them an idea what it means "to visit a site in the Internet".
The structure of the Internet: The Internet is a world wide network of millions of computers. Imagining it as a neat net - like the one of a spider - is nice and understandable and will be suitable enough for the beginning. Each of the knots in the spider`s web symbolize a single computer and the threads between them can be assumed to be the wires between those computers.
The very moment you read these lines your computer is (via the cable leading to your phone plug) connected with one of those knots and therefore a part of the Internet. In case you currently use a wireless Internet connection it is the same because your computer will send all traffic to a small box near to it, which is connected to the phone plug.
Clients und Servers: Each computer needs to send and to recieve data. So e.g. the text you are currently reading is something you have recieved. But before you got this information you needed to send the address of this Website to the Internet. You have done this either by entering the address manually to the address bar of your Internetbrowser or by clicking an Internet link on the previous website.
I admit that this communication is not very symmetric as you are able to get a complete Website with content you can display on your computer while I can not expect such service from you. But you can believe me I am just the same kind of computer like the one which is on front of you right now. The only difference between us two is that someone has stored some Internetpages on my harddisk and that I have a program running which makes me able to deliver the stored pages to you if you request them. You actually have requested the page "internet.php" and so I have delivered it to you. By the way: I can only deliver pages my programmer has stored here before. If you would ask me for a page like "sharks.php" I would send you an error message, because no one has stored such a page here and I am not able to invent some meaningful texts about sharks myself. As you can not be expected to guess the names of pages that are stored on my harddisk there is a link to all pages I have stored. Most of those links you can find in the menu bar at the left hand side.
On your computer a program is running right now as well - which is your Internet browser. It displays all the data you recieve from the Internet and leads all data you will enter right through to the Internet. So the only difference between your computer and me is that I have some pages with information stored on my harddisk and we are running different programs. Because my program allows me to serve data to other computers if they request them I am called a "server" or as I am accessible via the Internet an "Internetserver". The program on your computer (the Internet browser) is mainly made to request and display data thats why it is called a "client" - or if you like an "Internetclient" as you are in the Internet at the moment as well. In case you would install the programm I run on you computer as well (and prepare a bunch of webpages on your harddisk) you could be a server yourself. In case you would continue surfing with the browser you would even be able to be "client" and "server" at the same time.
Addresses in the Internet: As you already know all the pages you can request from me are stored on my harddisk. If you name me the correct page I am happy to deliver it to you. But how have you managed to find me in the Internet as there are millions of other computers there as well? And how comes the data your computer sends to your phone plug (remember asking for a certain website is sending data via the phone plug) is able to reach exactly me?
Actually this is quite simple because I have an address in the Internet as well. If you look to the address bar of your browser you will see my address right before the name of the certain page ("internet.php") you requested from me. So my address is http://en.web-fortbildung.de. The "http://" signalizes the language your browser wants to talk with me. But as we computers in the Internet mostly talk "http://" with each other it would be no problem if you would have skipped (saves your time when not typing it in) that information - your browser will complete the missing part then automatically. So you would also reach me at "en.web-fortbildung.de".
This leaves just one other question: how do I find you? Obviously I do because I as well send my data to a phone plug to the Internet which then via all the cables reach your phone plug and your computer. Again that is simple: Your computer has an Internet address as well (which is 184.108.40.206 at the moment). You get this address the moment your computer is connected to the Internet. If you wonder why I know your Internet address: your computer sent it to me along with the request to view this website. This was necessary because otherwise I would not know where to send the data to.
It is a great advantage that there is no direct connection one has to rely on. If it happens a route gets blocked or gets out of service it is still possible to reach the destination by using some other way. If that happens in the Internet in most cases you would not even notice any difference if the data takes a loop way because it is travelling very fast.
Each computer holds a list of computers it has a direct connection with. If the destination computer is not on that list the data will be sent to a computer of that list which have a closer connection to the destination. This computer will then do the same: if the destination is not directly connected with it it forwards the data to a computer closer to destination. This scheme is repeated until the data is delivered properly.
But there is a slight drawback in that method as well. It is possible for an intercostal computer not just to forward the data handed to it but to read and copy it as well. Hardly any computer would do so because you would need some amount of criminal intention to do so and most data spied this way would be useless for the interceptor. Additionally in most cases not all parts of the communication of two computers will pass the same intercostal computer. So if it logs any data it will then not have the whole communication but only fragments of it. Anyhow some data transfers are encrypted to avoid such spying. The intercostal computers would then still be able to intercept data but they could not decipher the original message.
To ensure that the destination computer will be able to read the encrypted data the two computers use a special protocol for their communication which is called "https://" (instead of "http://"). This is for example used for communication by most online banking websites when confidential data is about to be submitted. But you can only talk "https://" with a website that is prepared to do so. So for example this website provides no secret data and therefore was not prepared for encryption. So trying to communicate "https://" with this website would lead to an error message.
"They came to see and to be seen as well"