With computer programming, sometimes it's just a matter of finding the right combination. Using a home brew of Web technologies that have been around for years, developers for Google Inc. have crafted a stunningly interactive map of North America, E-mail on the Web with uncommon snap, and a search-engine feature that suggests a phrase after somebody types in just a few letters.

Now the company is releasing the API to Google Maps and some of the code behind Maps, Gmail, and Google Suggest, all written with a mix of software known as Ajax, short for Asynchronous JavaScript plus XML. Led by Web powerhouses like Google and Yahoo Inc., Ajax is helping change what companies can offer their customers online. Ajax makes software on the Web act like it's running locally on a PC. Users won't face that confounded spinning hourglass while drilling down on Google Maps and don't need anything fancier than a browser.

Google has redefined what Web applications look like, says product manager Taylor. Photo by Jeffery Newbury

Google Maps product manager Bret Taylor dares to call the step of clicking on a blue URL and loading a page "the old Web user interface," while software developed with Ajax feels like a desktop app. "We've really redefined what a Web application looks like," he says.

More software developers and Web users soon could get a taste of what Taylor is talking about. Microsoft last week said it's developing a programming tool code-named Atlas that will let its legion of Visual Studio users write apps using Ajax, which works by updating pages behind the scenes so Web sites can deliver new information to users in an instant, with nary a page refresh. Yahoo's photo-sharing site, Flickr, lauded for its ability to let users easily organize and share photos, recently switched large portions of its site from Macromedia Inc.'s Flash technology to Ajax. Yahoo also is preparing a major upgrade to its Yahoo Mail service, based on its acquisition last year of Ajax E-mail software company Oddpost Inc., in an attempt to match Google Gmail's speed.

Ajax can work for high-pressure business-to-business Web sites, too. Sabre Holdings Corp. is getting ready to release new versions of its airline-scheduling and -operations software that use Ajax to reduce response times from minutes to milliseconds, making screenfuls of flights instantly browsable. In May, Sabre started releasing some of its Ajax code under an open-source license to buff up its image as an IT innovator. "We broke through the performance issue and the usability barrier," says David Endicott, VP of product development at Sabre Airline Solutions, which develops software for airlines, including American Airlines and JetBlue Airways Corp. "It's raised awareness of our brand and who we are."

Often there's a brilliant programmer or two behind a new way to develop software. Ajax's roots are more diffuse. Its core technologies have been around since the 1990s, but evolving Web strategies and technologies are bringing them together in novel ways. Software design on the Web is becoming more important as Google, Microsoft's MSN, and Yahoo release high-quality software at a prolific rate and as companies try to boost their brand image and increase revenue through better site design. And since the browser wars have cooled, it's becoming more likely that any browser can reliably run what developers write. "User experience has been on hiatus on the Web," says Charles Fitzgerald, a Microsoft general manager. "Since the beginning of this year or a little earlier, you've seen renewed interest. There's a battle for customer attention."