Firstly I must point out that I am in no way advocating horizontal scrolling on web pages.
Assuming that you are using a screen resolution of at least 1024×768 pixels (96% of internet users worldwide in 2009), you will almost never see horizontal scrolling. This is because it has been recognised as highly unusable for some time. I wont be debating that here.
However, I take issue with the fact that vertical scrolling seems to have been tarred with the same brush.
Its extremely common for a client to request that users should not have to scroll to see any content on their pages (or a large majority of the content at least). This seems to be based on two assumptions. First is that users dont see content below the page fold (the point at which the content disappears behind the frame at the bottom of the web browser). Second is that users dont like scrolling and find it a chore.
Dispelling the myths about scrolling
Myth #1: Users dont see content below the fold
Lets take a look at the first assumption that users dont see content below the page fold. It is obvious that, when the page first loads, this assumption is true. It is impossible for users to see content below the page fold before they start interacting with the page. This is why the most important content should be placed towards the top of the page. This includes things like the branding/name of the site, navigation, search, login button, latest news etc.
However, users can start scrolling a page almost immediately as the content loads, and research shows that users absolutely do scroll. In fact Jakob Nielson noted that a propensity to scroll was becoming common in web users as early as 1997!
Myth #2: Users dont like scrolling
We have already seen that the overwhelming majority of users do scroll (and often to the end of pages regardless of length), so we can be sure that our content below the fold is being viewed. However, are we running the risk of annoying users? Do they scroll grudgingly? Heres a poll from About.com that tells us that only a very small minority of users do not like scrolling.
Users like scrolling because it is good for them
With mouse scroll wheels now so prevalent, scrolling has never been easier. Therefore, its not hard to see why users have no problem with scrolling. They are used to it.
Additionally, the alternatives to scrolling are far worse for efficiency and usability. Scrolling is actually good for users.
Believing myth number one often leads to extremely cluttered homepages, with every piece of content wedged in above the page fold*. Often this content isnt the most important, and it should not be competing with the crucial stuff. Instead it just impairs the impact of key information. For usabilitys sake, content needs room to breathe.
Believing in myth number two often leads to the introduction of a second level of navigation, or pagination. This is not helpful because it introduces an additional layer of complexity to navigating a site.
And finally there is the issue of time wasted while pages load. A user has to wait only once for a long article to load when it is published on one page. Granted the page will take longer to load with the whole article on one page, but thanks to the fact that HTML is loaded sequentially from top to bottom, users can begin reading the start of the content as the rest is loaded. If, on the other hand, the article was split over five pages, the user will have to wait for five page loads**.
Nobody likes waiting for pages to load – including (I suspect) even the small minority who hate scrolling.
* Something else to note about the fold on a webpage is that it is never in the same place for all users. Different users have different numbers of vertical pixels in their displays. My current screen has 1024 pixels of vertical space. My laptop, however, has 800. Therefore, the page fold will be in a different place for the exact same web page. Furthermore, users often have toolbars installed in their web browsers, which again affect the vertical pixel space available for a web page.
** This is particularly annoying on a mobile device. When you are subjected to a slow download speed, and also small pockets of connectivity (especially when travelling on a train). Its great to be able to download one long web page while you have a connection, and continue to read it while you go through tunnel after tunnel.