NOT SO WELL KNOWN

There's another rich contributor to the Web's function, but it's even less well known today than AltaVista. It's the XMLHttpRequest object.

Say what?

The XMLHttpRequest object first appeared in March 1999 as part of Microsoft's Internet Explorer 5.0 browser. The browser window before XMLHttpRequest was a static display, like a dumb terminal window. The only thing it could show was what the server sent it as an HTML page. As millions of users interacted with an Internet server, most of them were looking at the same handful of pages, none of them tailored to an individual user's requests as they are today.

XMLHttpRequest changed that. Initially an Active X control, it provided a way to open a background communications channel between the browser and the server over which data could be passed. Before XMLHttpRequest, about the only way a user could get different data was to request a different page.

With Internet Explorer 6.0, in August 2001, XMLHttpRequest was more readily available as a general purpose API instead of an Active X control. It followed Web standards, sought to move data between a server and client as XML or dynamic HTML using the HTTP protocol, and used only JavaScript (or Microsoft's compatible equivalent, JScript) for programming inside the browser window.

The pattern invoked by the API became the cornerstone of Google Maps' ability to respond to an individual end user's request for map data. The customizations that make a MyYahoo account seem tailored to an individual spring from that pattern. "It's the secret sauce of Web 2.0," says Pete LePage, Internet Explorer's senior product manager. Google, Zimbra, and dozens of smaller players are rushing to use the Request object, which in its Internet form is known as Ajax, to build online applications that compete with Microsoft's. "Microsoft probably hasn't received the credit it deserves for having invented XMLHttpRequest," says Scott Dietzen, president of Zimbra, an archrival. The World Wide Web Consortium is working on a standard that formalizes it.

How many examples of great Web software does that make? Four. Got to keep moving.

SIMPLE CONCEPT, COMPLEX CODE

The Web punishes complexity and rewards simplicity. But it doesn't reward only simple software; it rewards simple concepts wrapped up in complex software programs.

Exhibit A: On Sept. 3, 1995, computer programmer Pierre Omidyar established AuctionWeb on a personal site he ran to see if used goods could be sold online. What would eventually become eBay brought buyers and sellers together like no auction house before it. EBay not only provided great software that allowed people to sell their goods online, but it also extended APIs to third-party software makers to produce tools for managing large sets of goods online, such as inventory management or listing design tools. Other third parties provided tools for buyers to search for goods on eBay listings.

The accessibility of eBay auctions has been one of the strongest drivers of new users to Web commerce. Two billion items a year pass through eBay, which will generate an expected $7.2 billion in revenue this year.

Exhibit B: Launched in 1995, Amazon.com expanded the e-commerce capability of the Web by building a million-volume online bookstore and popularizing the shopping cart and checkout transaction processes. It then capitalized on its e-commerce system by extending it to other retailers. Borders, CDNow, and Virgin Mega are powered by Amazon's e-commerce system, and hundreds of additional retailers link into it via Amazon's e-commerce APIs. Amazon didn't just bring shoppers; it expanded shopping as a standard Web activity.

One Amazon enhancement in particular, known as affinity marketing, used the power of the computer to consult purchaser data stored in a database, sort through what buyers of similar items had purchased recently, then present additional choices to the customer before he or she finished shopping. The technique, a proven sales generator, has been copied at other innovative online businesses, such as Netflix.

Please note: Both eBay and Amazon are involved in ongoing patent litigation over aspects of their respective business models. Another tenet of great Web software: It's not always clear who invented it.