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Hey guys, it's Angela from the App Brewery.

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And in this lesson, we're going to deep dive into how exactly does the Internet work?

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So what exactly is the Internet?

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A lot of people think it's a cloud, something that's hanging around in the sky,

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it's super complex, super difficult to understand, but actually, that's not it at all.

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The Internet is pretty simple.

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All it is is just a long piece of wire,

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and wire connects different computers to each other.

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So you might have one computer that's in London and another one that's in Seattle, and they can talk

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to each other and transfer data through this giant wire.

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Now, some of these computers attached the Internet have a very special job.

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They have to be online 24 seven, ready to serve you all the data and files that you are requesting

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when you try to access a website,

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and these are called servers.

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And what they do is they serve you all the data and files you need to be able to access and interact

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with certain websites.

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So these computers are called servers, and any computer that a user would use to access the Internet

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is called a client.

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Now, you can imagine a web server as a giant library that's open 24 seven, and you can go in there

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at any hour of the day and say, I want to see Google's home page or I want to see the latest posts

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on TechCrunch and would be able to serve you with all the files and data you would need to be able to

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view whatever website you want.

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Now, as you can imagine, if there's a library that's big enough to house all of these websites, then

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it's going to be pretty difficult to quickly locate the thing that you want out of this giant library,

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right?

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So how is this problem solved on the Internet?

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Well, let's say that you're sitting at home on your computer and you type in Google.com because you

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want to head over to the main Google home page.

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Well, what happens behind the scenes is that your browser will send that message to your ISP or your

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Internet service provider.

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So these are the people who you pay to be able to access the Internet.

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If you live in the US, that will be ATandT or Comcast,

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and if you're in the UK, that would be something like BT or TalkTalk.

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Now the message that you're sending the ISP is I want to see Google.com and the ISP will then relay

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that message to something called a DNS server, which stands for a domain name system server.

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And a DNS server is essentially just a souped up phone book.

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And what happens when you make that request through your browser is the DNS server will look up in its

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database to find the exact IP address of that website that you're trying to access.

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And every single computer that's connected to the Internet has an IP address.

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It's kind of like a postal code for your computer so that when people need to send and receive files

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on the Internet, each computer can be located and contacted using their unique IP address.

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And once the DNS server finds that IP address, it will send it back to your browser through the ISP,

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over the internet.

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Then you can make a direct request to that address.

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And what lives at that IP address is of course the Google servers, and they'll be able to send you

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back all the files and data you need to be able to view the Google home page.

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Now you can try this for yourself to look up the IP address of the Google home page. Head over to this

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website, nslookup.io and type in Google.com and they should show you the exact IP address of the Google

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servers that you can access.

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So if you copy it and paste it into a new tab, then you'll be able to replicate that process and see

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the Google home page show up.

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So to summarize, the Internet is just a bunch of wires that connects up different computers, but it's

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just on a much bigger scale connecting up all the computers in the world.

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But what about the oceans?

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I hear you ask.

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Well, that's one of the coolest things.

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There are these massive undersea cables connecting all the continents on Earth.

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And if you head over to submarinecablemap.com, you can see all of these cables and see the ones

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that connect you up to the Internet.

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And these undersea cables are massive, consisting of hundreds of fiber optic fibers, each of them

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using lasers to transmit up to 400 gigabytes of data per second.

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This is a cross-section of one of the cables that runs to New Zealand.

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It's an absolute marvel of modern technology, and it looks really beautiful, don't you think?

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And to think that every single time we load up a web page or click on a button on a website, behind

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the scenes was sending signals that navigates all of this crazy underwater and above water wires

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and all I need is just an IP address.

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And through tiny electric signals, traveling at the speed of light through the oceans and halfway around

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the world,

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in a matter of milliseconds, I get to view my favorite websites, and that is how awesome the Internet

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is.

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And we're gonna be taking it to build our own websites and web apps.

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And to be able to do that, we first have to understand how exactly do websites work.

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So for all of that and more, I'll see you on the next lesson.