How the Internet Works

If you've ever felt like you spend too much of your time on the internet, you're in good company. A 2007 report by communications industry regulator Ofcom found that the average Brit uses the internet for 36 minutes every day.

It's perhaps not surprising. Connect your computer to the internet and you can use it to check that you've been paid, book a holiday, track down the latest films and music, or exchange words, pictures or videos with friends and family around the world... in fact, it's probably shorter to list the things you can't do on the internet. But how on earth does it all actually work?

A big collection of computers shuffling data around might not sound so exciting, but ever since the internet's beginnings at the end of the 1960s, people have been inventing new ways to use it.

Today, one of its most popular uses is carrying the information that allows people to view pages on the World-Wide Web, like this one. In fact, many people now use the terms 'internet' and 'web' interchangeably, even though they mean slightly different things. The World Wide Web wasn't invented until 1989, but looking at its workings also reveals how the internet operates.

Web of opportunity

Every computer connected to the internet has a unique address, known as an IP address, but these long numbers don't make as much sense to humans as web addresses based on words, like btbroadbandinformation.com. On the web, an address like this is known as a domain. When you clicked on a link to this page or typed its address into your browser, the first thing that your computer needed to do was to find the real address of the computer that stores our website.

It did this by contacting a special computer (a server) belonging to your internet service provider (ISP), which keeps a list of all the publicly known domains and the IP address of the computers that host the websites, email systems and so-on for each. This domain name system (DNS) server replied with our IP address. Once your computer had this, it knew exactly where to send your request to see our web site.

Unless you're Harry Potter, when you send a letter it doesn't travel in a straight line between you and the person it's meant for. It's much the same on the internet, where packages of information pass along established cables between routers - a kind of digital sorting office. These check the address on the package, and send it on towards its destination down the most sensible route. Depending how far you are from our London-based web server, this journey might have taken anything from 10 to 30 or so 'hops'.

Once our web server received your request, it began to send the text, pictures and other information that makes up this web page back to your computer, using a return address supplied by your computer when it sent its original request. If all went well, your browser was able to re-assemble all of this into the wonderful web page you see before you.

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