What is the Internet?

While more people have access to more information than ever before on the Worldwide Web, it's still the case that many people struggle to answer the question: What exactly is the internet? Most people are familiar with the idea that you run a program on your computer called a web browser and that gets you online - but how? We sent Naked Scientist Timothy Revell on an internet search to find out. He began by asking some members of the general public for their views on what the Web is...

Boy 1 - It's like a spider's web with loads of different connections to different places with answers in and also, other stuff.

Boy 2 - An internet is where you can go online like you talk to people on the computers.

Woman - It's everybody's computer. Everyone's server is all linked up together.

Man - It's a load of connected websites.

Girl - You click literally on the internet button which is on every iPhone and iPad and computer and it hits you onto some webpage.

Timothy - The "internet button". That's exactly how I see the internet, and I know a lot of other people do too. It's a miracle of modern technology that with just a single click, you have access to what we call the internet. But I wanted to know more. Is the internet really just a button?

Andrew - The best way to think about what the internet is, is to think about what it does.

Timothy - Let's talk to Andrew Rice. He's a lecturer at the University of Cambridge computer laboratory.

Andrew - When you connect your computer or phone to the internet, this enables you to send a message to any other machine on the internet as well. This is actually quite an achievement. To send a message from the UK to the USA, it might take 20 different machines called routers to pass your message through and this will travel through the telephone network, to dedicated computer links across the country, and fibre optic cable under the sea. All of this and your message is delivered in under a 10th of a second. So, what does the internet do? It allows us to send messages between connected machines with other connected machines and it does this by building what's called a network of networks.

Timothy - A network is just two or more computers that are connected so that they can talk to each other. The connection might be via a physical cable or by using some form of wireless technology. If we have two or more networks talking to each other, we call that an interconnected network, or internet for short, which seems pretty simple. But I'm still left wondering, what happens when you actually visit a website? Let's grab a keyboard and find out. First, let's connect the computer to the internet. Oops! Sorry, I had my computer set on 1990s mode. Now we're connected to the internet, let's type inwww.silkstaq.comand hit ENTER. Then as if by magic, the Naked Scientists homepage appears. But let's slow things down a little. To find out what's actually happening, I spoke to Rob Coupland, the managing director for TelecityGroup. They run a highly secure data centre in London which, I have to tell you, is a little bit loud.

抢劫,我们站在这里的建筑基本上y a meeting point where all of the various networks that carry the internet traffic come together and it's really the place where those networks swap traffic with each other. Now, to make that work, they have a system of addresses that are known as IP addresses which are very meaningful to computers that love to work in numbers. But actually, from the point of view of a human being, they're pretty meaningless. So, the first thing that happens when you press ENTER is that web address that you type needs to be turned into an IP address. There's a system known as DNS - domain name server. The best way to think about that is that it's the internet equivalent of the phonebook and if you think about, if I were trying to call you, I wouldn't have a clue what your number was, I get the phonebook out, look up Timothy in there and it gives me the number, and then I press the number into the phone and we're awake.

Timothy - To give an example of what Rob is talking about, when you visit the Naked Scientists website, the electronic phonebook looks upwww.silkstaq.comand finds the IP address which is 81.201.132.24, which is a bit of a mouthful and not very easy for a human to remember. But it's great for a computer, because it tells it exactly where to find the Naked Scientists website. Once you know the IP address, your request to view the webpage can be sent to the right place.

Rob - What happens is that the data gets chopped up into what are known as packets which are exactly what they sound like. They're neat little parcels of information which have an amount of data in there, and what that packet has is very much like your envelope. It has an address on it that says, where is that going to and also, information about what order the packets should go in. so that when they arrive at the other end, then the computer will reassemble them and then provide the data through to you in the right order.

Timothy - In other words, the host of the website takes the webpage.

Recording - "nakedscientists.com"

Timothy - Breaks it up into small pieces...

Recording - "na - ked - scien - tists - dot - com"

Timothy - Then places each of those pieces into a packet. Each packet is then labelled with a destination address, a return address and how it fits together with the other packets. These are then sent through the internet at break next speed to reach you out to your home. Not every packet takes the same route and so, they may arrive in the wrong order. And some may not arrive at all.

Recording - "tists - na - sci - om - dot..."

Timothy - But once some packets do arrive, your computer asks for any missing packet to be resent. All of this happens in a split second and so, all you see is the Naked Scientists website, appear in its full glory.

Recording - "nakedscientists.com"