Newspapers put their best stories (the ones most likely to sell issues) on the front page, above the fold. In other words, since most newspapers are folded in half, you can only see the top half of the paper from a newspaper box. That's the half that the top stories have to be on, because it's the part that people will see first.
As AOL's Milissa Tarquini points out, the same basic principle has traditionally been applied to web sites. But things become a bit complicated when you think about all the things that need to be "above the fold" online. With a newspaper, once you've convinced someone to buy the paper you've already got their money (and the money advertisers are willing to pay for their eyeballs).
Online, you need to grab their attention with your content, describe what your site is about and why they should keep coming back, and in many cases try to make revenue. That means you need a combination of branding, advertising, and content all to come above the fold. Doesn't leave as much room for content as you may like.
And then there's the trickier issue. Where exactly is the fold? While most users may be reading your site on displays with 1024x768 resolutions, there are many computers with higher, lower, or widescreen variations. And that's not taking into account the many different web browsers people may be using. Internet Explorer, Firefox, Opera, Safari, and Konqueror all have different toolbars atop the screen affecting the size of your display window. And in many cases users can customize those toolbars so that two people reading your website using Firefox on a 1280x800 widescreen laptop might still have different "folds."
But here's Tarquini's little secret. People know how to scroll. Shocking, but true. While you probably do want to grab a visitor's attention right away when they land on your site, you don't need to kill yourself trying to fit everything into the top few hundred pixels on your screen. If they're even vaguely interested, readers will scroll down the page. In fact, she says the top link on TMZ is all the way at the bottom of the page. It says "Next Page."
[via Information Week]