Chapter 1 - Pete - How Does The Internet Work - v1.0.docx

**Chapter 1 - Pete - How Does The Internet Work - v1.0** All roads lead to Rome, they say. It\'s a saying you\'re probably familiar with, and for a good part of classical antiquity, it accurately described the state of that period\'s communication networks. Nowadays, however, these exact same roads...

**Chapter 1 - Pete - How Does The Internet Work - v1.0** All roads lead to Rome, they say. It\'s a saying you\'re probably familiar with, and for a good part of classical antiquity, it accurately described the state of that period\'s communication networks. Nowadays, however, these exact same roads, or at least the fiber optics buried beneath them, lead not to Rome, but rather to the domain name server of your choice. Now, that\'s not nearly as evocative. What are fiber optics, and what the heck is a domain name server? These, and a lot of other very technical sounding devices, are what the internet is actually made of. Paradoxically, if you ask the internet itself what it\'s made of, you will likely, and incorrectly, be informed that it\'s made up of cats, trolls, and memes. Now, one does not simply attempt to explain the internet based solely upon its content. That would be like trying to explain how a television set creates its visuals by describing the romantic relationships in your favorite soap opera. We must first separate the technology from the content. When we want to know more about some topic, we\'re often told to just check the nets, or look on the web. These two statements refer, of course, to the internet and the world wide web. These two terms are often used interchangeably in everyday conversation. To be on the nets or to be on the web is taken to mean the same thing. But technically, they represent two very different things. On the one hand, you have the world wide web. This web, abbreviated www at the beginning of many of the addresses you type into your browser, is similar to all the soap operas, the news channels, the movies, and the questionable reality shows you watch on your TV. So, the content. The world wide web is the sum of millions of interconnected web pages, providing you with all the information or entertainment you\'re looking for. The internet, on the other hand, is closer to what the television set in our little example would represent. An actual network of physical devices connected to each other by real cables or by satellite signals. These physical devices all exchange information with each other, in some creating a massive, world-encompassing physical labyrinth or network. In other words, the internet can be described as a global network of interconnected servers, computers, data centers, and network protocols, all of which serve as the basis and infrastructure for all the information which is hosted on it and which travels across it through copper wires, fiber optics, satellite connections. Effectively, the internet\'s roads. We\'re going to look at what each of these components are and how they\'re connected, but it might help to start with a tiny bit of history. In the second half of the 1960s, the Cold War was at its height. Both America and the Soviet Union owned a bucket full of nuclear weapons, ready to be launched at the press of a button. The thing about nuclear weapons is, when they blow up in your backyard, the telephone lines usually don\'t work so good anymore. Even if you\'re the U.S. Army. So the U.S. decided to build a communication network that would work even if a nuclear bomb detonated within its borders. It created an entire network of nodes of different centers around America that all the other communication devices are connected to. They then pass it on to other devices. The advantage of the system from a nuclear war perspective is that it\'s decentralized. Even if a nuke lands directly on top of one of these nodes and blows it up, the data from the other communication devices can instantly be rerouted to a different node, one that hasn\'t been blown up yet. The first such decentralized network was called ARPANET, and it opened for business in 1969. It only had four nodes in the form of universities. But over the following decades, more and more nodes and participants were added. Universities, private companies, and finally even ordinary people like you and me were able to participate in this huge network. Soon enough, this network extended beyond the USA and covered most of the planet. And this brings us to this very moment where every single one of you is watching me on a device connected to this global network. So how does it work? As we\'ve said, the internet relies on hardware, software, protocols, and infrastructure to do its thing. Let\'s walk through it, starting with you at your PC. Let\'s pretend that you are located in Vienna, Austria. You want to look at the web page of a samba dance group that lives in Rio de Janeiro, Brazil. How do we get that website from Brazil onto your screen in Austria? Before we continue with how the data of websites travels around the internet, remember that physically all data exchange happens using electrical signals in the form of bits or zeros and ones. These electrical signals travel between all the components of the internet like servers, routers, and data centers through copper cables, or as light through fiber optic cables, or as radio satellite signals, and carry your requests and data from computer to computer. The internet is just a giant network of physically connected computer systems. To understand how the internet\'s communication works, we need to look at how your data travels around this internet on the software level, since that\'s what brings the internet to life. Let\'s use an application you already know, like a browser. So step one. You type in the web address of the website which you want to visit, known as the URL or Uniform Resource Locator, into your browser. It looks something like this. You can think of the URL as a unique street address of a house, or like a specific telephone number which your browser needs if it wants to reach some website. And here\'s an important thing you need to know about how URLs work. In your phone, you have a contacts list which has all the telephone numbers of your friends, right? Why do you need such a contacts list? Well, because you simply can\'t remember all those long strings of numbers by heart. It\'s much simpler to just remember the name of your friend, and your phone automatically dials the telephone number associated with it without you having to remember it. And it\'s exactly the same with the web addresses. The sambadanceparty.com in the is what we call the domain name. And it has exactly the same function as the name of your friend in your phone contacts list. It\'s easy to remember. And like your contacts list, this domain name also has a sort of telephone number associated with it. This number is the real address of the website. It\'s called the IP address, which stands for Internet Protocol Address. So, step two. After you enter the URL into your browser, it first needs to find out this real IP address of sambadanceparty.com before it can take you there. Your browser doesn\'t know all the IP addresses in the world, so it needs to ask someone who does. Step three. In the form of electric zeros and ones sent through an internet cable, your browser sends out a special request to your ISP or internet service provider. Your ISP is the company which connects your computer to the internet. The request your browser sends is, please connect me with someone who knows the IP address of sambadanceparty.com. Your ISP obliges and connects your browser with what amounts to a gigantic contacts list for the entire internet. The Domain Name System or DNS. The DNS looks up the IP address which corresponds with your website\'s name in its huge list and sends that information back to your browser. It says the IP address of sambadanceparty.com is 142-250-189-174. Step four. Your browser now again contacts your ISP, but this time it tells it, please connect me with the web page which has this exact IP address. Step five. Your ISP now sends your data to this destination IP address, but it\'s not a simple direct connection. Before your browser can finally talk with sambadanceparty.com, it has to travel through many other parts of the internet. Your data travels from your PC to your ISP over copper fiber optic cables. From there to other servers which direct your signals along many other nodes and routers. It arrives at a data center somewhere on the western shore of Europe where it is then sent along huge undersea internet cables across the world to the final destination. Step six. Your browser\'s request for connection has finally reached the website you were looking for. Specifically, it has reached the server or the computer on which all the website data is stored. There, your browser is introduced like a guest to the website. In our case, sambadanceparty.com says, hello visitor, what can I do for you? Your browser replies with a request. My user would like to see your front page so I would like to request all the text images and the design style so that I can display it on her screen. Step seven. The website sends all the requested data back to your computer. Again, along a complex system of cables, networks, and servers. Where browser receives it and instructs the graphics card on how to display it on your screen with all the correct pictures and formatting. Your computer remains connected to the website and anytime you click on one of its links or videos with your mouse, your browser sends another request for more of that website data which the website again sends back to you. Back and forth across half the world in an eye blink.