What is the difference between the world-wide web and the internet?

E-mail, file transfer protocols, chat-rooms and internet phone services are all parts of the internet. But the largest, and most often used part, is that bit which you see with your web browser. This shows you text, pictures and video and has links that can take you to other websites. It is this set of links all joining website to website that gives the World Wide Web its name.

What are 'clients' and 'servers'?

If you want to see a web page, you need a computer, and some software to get the page off the internet. Because this software goes to the address where the web page is kept and asks for it, it acts like a customer, or client. The computer which gives the data to the client serves it, just as a waiter serves you fish and chips at a restaurant.

Tell me about IP numbers and URLs.

A server needs to know where to send the data which a client has requested. To make sure this data goes to the right computer, every computer on the internet at a particular time has its own number. These 'IP numbers' are always in groups of three or fewer, and are never higher than 255. Because people are not very good at remembering numbers, web sites also have names which make them easier to remember - these are called Uniform Resource Locators. They are actually a bit of a nuisance for computers which have to keep translating between names and numbers!

Why do some URLs end with two letters, and some with three?

URLs should show which country they are from. So a URL in Brazil will end with .br. British urls all end with .uk. However, because the internet was invented in the United States, all servers were originally .us. When the internet expanded, it was too inconvenient to rename all these URLs so the US remains the only country where URLs don't have a a two letter suffix. However, because some originally US names like .org and .com are so widely used, now they can be from anywhere.

So the World Wide Web was invented in America?

The internet was invented in America, but the World Wide Web comes from Switzerland, and it was mainly the project of an Englishman called Tim Berner-Lee. The scientists he worked for wanted a way for physicists to share information easily. But Mr Berners-Lee realized that the Web could be used for a great deal more than that, and always wanted the web to be a data resource for the world. The world's first web server was www.info.cern.ch which was started in 1990, and the first web page showed the telephone numbers of the staff at the research centre.