(FORTUNE Magazine) – I'm on my way, I'm making it I've got to make it show, yeah So much larger than life I'm going to watch it growing. --Peter Gabriel

Every five to ten years the computing world undergoes a discontinuity that dramatically affects the information technology landscape. As we shifted from mainframes to minis, minis to PCs, and from PCs to client-server systems, new leaders were born and old players were put to rest. At first, these phase shifts are subtle. However, little by little, financial backing and human resources are committed to technologies that are different from the status quo, and these new architectures gain so much momentum that they become the new reality.

The most obvious source of recent technological change is the Internet, and at first many experts thought the browser would be the fulcrum of this change. But the test of a discontinuity is whether the competitive landscape is changed, and Microsoft moved fast to ensure that the browser alone didn't cause a fundamental shift.

The real technical discontinuity created by the Net may be just emerging--but rather than happening on the browser end of things, it's happening on big Websites. To date, most Websites work in a way that's similar to a client-server application. There is a server that offers up Web pages, a bunch of applications written specifically for that site, and a database that those applications draw from. Recently, however, something different has emerged on large Websites, like those of Yahoo, Amazon, and Dell. These are completely different creatures. Welcome to the world of Big Fat Web Servers (BFWs).

These sites aren't run by a single Web server, but by Web farms: hundreds of servers linked together in a highly complex environment. Engineers struggle to ensure that the site is running smoothly, that each server carries an appropriate load, and that there are no bottlenecks.

These BFWs represent something genuinely new in the history of computing. It might best be described as a high-end complex machine fine-tuned specifically for the task at hand. As an analogy, consider the air-conditioning system for a skyscraper. The premise behind distributed computing would argue that you could take hundreds of air conditioners built for a single-family home and scatter them around the building. Of course, this is not what happens. HVAC specialists work with architects to construct high-end systems that work for the particular structure. This is now the principle behind creating and maintaining large Websites.

In terms of elegant technological design, the move to BFWs is in some ways a step back. Client-server computing is designed to provide a company with flexibility. The design of BFWs, on the other hand, is governed by one, and only one, consideration: speed. As the number of users grows on a Website, the engineers typically adopt a by-any-means-necessary attitude. Elegant computing takes a back seat to innovative hacks when the goal is to serve your customer quickly.

If you think this is a temporary phenomenon, think again. We are in the very early days of BFWs. Corporate and venture capital dollars are pouring into large Websites. E-commerce companies are popping up like dandelions. Every corporation realizes it needs a major Web presence to communicate with partners and conduct transactions. If that were not enough, software applications will increasingly look like Internet services, rather than like the stand-alone applications we're used to. Businesses, for instance, may rent a financial application that resides on another Website, rather than install and implement a software package on its premises. This implies less dollars allocated to enterprise software and more dollars flowing into BFWs.

In order to rank as a true discontinuity, the BFW movement must affect the competitive dynamics of the computer business. This process has already begun. Sun Microsystems was once dismissed as a victim of the PC revolution. But it makes the servers that power many Web farms, and its stock has soared from 40 to 100 since October. Oracle, whose databases hold the info BFWs depend on, is bouncing off a 52-week high--while most of its peers in the enterprise software market are trading at near 52-week lows.

Another interesting development is the rise of open-source computing. The operating system Linux and the popular Web server Apache are based on source code that is free to all users. Why does this appeal to the people who create BFWs? Because it gives an engineer the flexibility to open the hood of his Web farm and see whether a couple of tweaks will allow users to check out a few more pages per minute. BFW designers need customized tools to build their data skyscrapers.

Microsoft is the company most threatened by the rise of the BFW. Its Web server, called SiteServer, bundles most of the features that a BFW designer would want. The problem is that BFW builders find it more difficult to pull apart this Swiss-army knife of applications than to customize their site from a set of components.

It would be premature to predict the death of distributed computing. But it is important to realize that in a world of increasing bandwidth, centralized data make more sense than distributed, Web services make more sense than desktop applications, and investing incremental dollars in BFWs makes more sense than spending on small stand-alone machines. We are on the verge of a new discontinuity. New companies will be created, old companies will stumble, and the technical jockeys that can tame the BFWs will be the new heroes of the 21st century.

J. WILLIAM GURLEY is a partner with Hummer Winblad Venture Partners, a venture capital firm. Except as noted, neither he nor his partnership has investments in the companies mentioned. To receive an expanded version of his column, Above the Crowd, visit www.news.com; to subscribe to the e-mail distribution list, send e-mail to subscribe-above_the_crowd@atc.revnet.com. If you have feedback, please send it to atc@humwin.com.