4. The Web: An Ocean of Information

The great thing about the World Wide Web is that, beneath all the hype and hoopla there is a very simple idea at work--an idea called hypertext.

Now we all know what written text is: letters, numbers, punctuation marks and so on. These are strung together in a particular order to produce words, sentences, paragraphs, chapters and even whole books--just like the one you are holding in your hands. But stop for a moment, and take another look at that phrase ``in a particular order''.

When we read a book we usually start at the beginning, work our way through the middle and end up at the end. It's as if there is a straight line through the book, showing the order. This is called ``linear text'' to indicate the idea of an implied ``line'' or order to read it in. This is so obvious and so essential to the whole idea of a book or an article that we usually don't even refer to it explicitly at all. But not all texts are like this.

To see the need for ``non-linear'' texts, think about using a reference book such as an encyclopedia or a telephone directory. It would be very tedious--to say the least--to have to start at the start of the phone directory and work ``linearly'' through it, in order to find the number of your friend Ziggy Zoziemus. Or to find the encyclopedia article on xylophones. So, of course, you don't do that: instead, you jump into the book at (more or less) the correct point.

With the phone book this relies mainly on simple alphabetic ordering. With the encyclopedia it is made easier by providing an index. Once you find xylophone in the index, there is a reference (a page number) that allows you go directly to the article. That article may then direct you to other related articles--perhaps to the composer, Igor Stravinsky, who introduced a xylophone into his ballet Petrushka in 1912 (yes, I just looked it up in my encyclopedia). This cross-reference can also have a page number, so that you can immediately jump to that article. That one in turn can be linked to others (Diaghilev, Jazz, 20th century music...) and so on.

For a large encyclopedia things get more complicated. You may need a volume number as well as a page number to locate an article. Then perhaps there will be references to further readings which are not contained within the encyclopedia itself--other books, sheet music, recordings, videos, pamphlets and so on. We are now talking about something like the card catalogue in a library. Once you find the right card, it effectively gives you directions on where to go in the library to find the particular book. Then, if you know the page number you want, you can jump right in.

You should be getting the idea that a lot of information in the world can be accessed in a variety of alternative orderings. You don't always have to follow the ``obvious'' ordering of the way the pages happen to be glued together to make a book, or the way the books are ordered on a library shelf. This idea of a text with many different entry points and many different pathways through it, is called a hypertext. The ``hyper'' is just a fancy label to distinguish it from a ``linear'' text. There is nothing complex or mysterious about it. The chances are, you have been happily using hypertexts all your life. It's just that nobody bothered to dress them up in this obscure jargon before now.

Hypermedia is just a small further extension of the hypertext idea. Here the blocks or pieces of information need not be limited to just textual materials, but can include other types of information, such as pictures, audio, animations and even video clips. The whole collection just has to offer multiple alternative pathways through it, by following ``hyperlinks''--references from one arbitrary position to another--for it to be called ``hypermedia''.

So: hypertext and hypermedia are nothing new, and are not somehow unique inventions of the computer age. Your local library, with its books, photographs, paintings, audio and video tapes--and card catalogues providing connections between them--is one big hypermedia collection.

All the same, the computer age has made a big difference. Think again about using ``hyperlinks''--cross references--within a conventional book. Certainly, it is a lot faster to jump to a page number than to have to read from the start to the point you want, but it can still be awkward. It is tolerable enough to follow links within one volume. It becomes a lot slower to follow links between volumes in, say, a 20-volume encyclopedia. And to follow a link from an encyclopedia to, say, a painting in an art gallery may involve a trip of thousands of miles, and take months or years in the planning and execution.

Electronic, computer-networked, hypermedia (phew!) change all that. First of all, hyperlinks within the ``same'' work can be followed instantaneously--no searching for the correct volume, no tedious flicking through to the correct page etc. Just use your mouse to point at the hyperlink or cross-reference, click on it, and presto, you're there. Better yet, a computer is just as happy to display sounds, pictures and videos as to display plain text. So you can follow a hyperlink directly to any of these kinds of information just as easily--you don't have to start up an entirely different machine to, say, listen to music.

Now imagine that all of the information you might want to refer to is already available in electronic form, on some computer somewhere in the world. Imagine that all these computers are connected together by a network. Imagine that there is a standard way of describing exactly where each piece of information is located--such as the shelf-marks in the library, combined (if necessary) with the volume and page numbers. Imagine that this works to exactly locate any kind of information, on any computer, anywhere in the world. Using these globally standardised references, you can follow hyperlinks between completely different sources of information, located in completely different parts of world, just as easily as you can follow links within a single book or document. Better yet, your computer can do it for you: just click on the hyperlink and your computer will contact the right server, and download the information you want. No matter where in the world it is, you could view it right from your own desk.

Imagine all of that, and you have imagined the World Wide Web! Well, that's the big idea. Now I need to get down to specifics.