A webpage has an optimum length and it is precisely, um, about that much. In other words, it’s impossible to define but you know it when you see it.

('Impossible to define but you know it when you see it' is a phrase commonly applied to pornography. A tutor on my degree claimed, in all seriousness, that it was also applicable to an elephant. I don't think he really 'got it'. We got into a debate about language. If you don’t share a common language, it's impossible to define anything; that's the reductio ad absurdum of the dictionary business. For the record, an elephant is a large, grey mammal of the genus Pachydermus. Where was I?)

As a general rule of thumb, a good webpage is no shorter than about half a screen and no longer than about two screens. Of course, screens come in different sizes, which is what makes this so approximate.

A page is somewhere that people find themselves when they click a link so it should have enough information on it to justify their having clicked that link. The ideal page has all the information that the site user wants right now, links to all the information they might want next – and no information that they don’t want.

A page that has just a line or two of text makes the user feel they've wasted their time. If the only information about subject X is a couple of sentences then it needs to be either grouped onto a page with subjects Y and Z or made available on the page about meta-subject X-1 (the next level up). Don’t make me go to a whole new page for a fragment of information that you could have published, without seriously affecting the design, on the page I just clicked from.

The only thing worse is a page with just one link on it. Sometime you find pages that have one link and nothing else. That's like opening a door to find a small, unfurnished room with one other door in the opposite wall. When will you architects learn!

But too much can be as bad as too little. About one and a half to two screens is great. There was a time when the message was 'nothing below the fold', ie. everything on one screen. But users know how scroll bars work – they can scroll down to find more stuff. In fact there's a real problem if you have exactly a screen's worth of content (for some value of screen size) because people will assume there’s more 'below the fold' and get confused when there isn’t.

A variant of this can be seen at www.percygee.org where 'the fold' is the break between an overly large amount of page furniture and the page text. So when you go to a new page within the site, nothing seems to change. That's just… bad.

People don't mind scrolling but they don't want to scroll on down incessantly. After a bit, they start thinking: why hasn't this information been broken up into smaller units? Anything sufficiently detailed and complex that it requires more than two screens to convey is, ipso facto, sufficiently complex that it can be broken down into two separate pages.

Not too much, not too little. A good webpage is about, um, this big.