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The Internet

The Internet is the communications network that lies behind your computer and connects you to the outside world.

In the beginning, it was a few computers connected together in one building and swapping text messages. Now there are millions of computers connected around the world using fibre optic cables and satellite links to transfer digital information - text, sound and video.

What's amazing is that this huge network runs on technology and techniques that were defined in the very early days, but which have been adaptable enough to cope with such a massive increase in complexity.

Domain names and IP addresses

Domain names and IP addresses : what's in a name?

There are now millions of computers connected to the Internet, and any of them can communicate with any other.

The system that's used is like a postal service - providing you've got an address, letters will get to you. Your electronic address is called your IP (Internet Protocol) address, and it's listed in an address book or directory called the Domain Name System. So if you want to send something, you can look here to find out exactly where to send it.

In fact, this is done for you. An IP address is a long set of numbers that's difficult to remember. So what happens is that you remember something simple like an e-mail address, and this is translated for you into the exact IP address by a computer called a Domain Name Resolver, which simply looks in a copy of the address book. There are thousands of these DNR computers - the company who supplies your Internet connection has got one.

Web page and HTML

The World Wide Web - HTTP and HTML : where do the pages come from?

The World Wide Web is the Internet program that caught everyone's imagination in the 1990s.

It's really a huge global library of information pages. Each page is stored somewhere in a special code called HTML (Hyper Text Mark-up Language).

This language can be read by a computer program called a 'browser'. The two most widely used are Internet Explorer and Netscape, but there are others such as Opera. The browser reads the HTML code and turns it into a page of information that it displays on your screen.

As in a library, before you can read a page you have to find it. Its location is the page's Web address. Once your browser has this it can work out where to go, and sends a request over the Internet. The computer that stores the page receives the request and sends the page back - and this is what the browser places on your screen.

e-mail (SMTP & MIME)

e-mail (SMTP & MIME) : 21st century post office

Aside from the World Wide Web, the computer programme that people use most is their e-mail. As every computer connected to the Internet has a unique IP (Internet Protocol) address, it's straightforward for your e-mail programme to send a message there, and for the Internet postal system to deliver it.

Early e-mail systems could only send text messages. If you wanted to send a package you had to use a slightly different approach. More recently, however, you're allowed to attach a package to your e-mail. And as long as it's wrapped up separately, it won't get jumbled up with your letter or any other packages you might be sending. This is what 'MIME encoding' does - it stops your browser trying to turn the wrong sort of information into readable text. It's a bit like stopping your sound system CD player from trying to play a CD-ROM computer game.

How does the Internet connect? : taking the right router

How does the Internet connect? : taking the right router
fun and games

Can you beat our games? Explode equipment to see what's inside, hear the changing sounds of telecommunications, see how telecommunications designs have changed over time or send an e-postacard.

what's on

The UK's first permanent gallery dedicated to the history of information and communication technologies opens in the new Information Age gallery at London’s Science Museum.

audio history

Take a trip down memory lane with extracts of the interviews which have been recorded as part of the Connected Earth oral history programme.

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