A year and a half after Steve Jobs endorsed it in an unusual essay, a set of programming techniques called HTML5 is rapidly winning over the Web.
The technology allows Internet browsers to display jazzed-up images and effects that react to users' actions, delivering game-like interactivity without installing additional software. Developers can use HTML5 to get their creations on a variety of smartphones, tablets and PCs without tailoring apps for specific hardware or the online stores that have become gatekeepers to mobile commerce.
That promise—and the lure of Apple Inc. devices in particular—is sweeping aside alternative technologies. In the latest development, Adobe Systems Inc. said Wednesday it will pull back on pushing the rival Flash format opposed by Mr. Jobs for mobile devices.
"HTML5 is a major step forward," declares venture capitalist Marc Andreessen, who helped invent the first successful browser, Netscape, in the 1990s.
Another Silicon Valley investor, Roger McNamee, predicts the technology will let artists, media companies and advertisers differentiate their Web offerings in ways that weren't practical before. "HTML5 is going to put power back in the hands of creative people," he says.
Many companies are placing bets. Amazon.com Inc. used HTML5 for a Web-based app called Kindle Cloud Reader that sidesteps Apple rules for selling content on its iPhone and iPads.
Angry Birds" creator Rovio Entertainment Ltd. developed an HMTL5 version that lobs avian projectiles at enemy pigs with no need for an app. Pandora Media Inc. used the technology to overhaul its popular Internet radio website, which launches more quickly and helps users more easily track others' listening patterns. Publications including Playboy and Sports Illustrated used HTML5 to let online readers boost the size of photos and rapidly flip through them.
The trend has been fueled by Apple, Google Inc. and Microsoft Corp.—rivals that more often disagree about technology choices—by building HTML5 support into their latest Web browsers. So have the Mozilla Foundation, maker of Firefox, and Opera Software ASA.
Some 34% of the 100 most popular websites used HTML5 in the quarter ended in September, according to binvisions.com, a blog that tracks Web technologies. Resume searches by hiring managers looking for HTML5 expertise more than doubled between the first quarter and the third quarter, according the tech job site Dice.com.
The excitement has spread despite the fact that HTML5 is missing some key features. Many users, moreover, won't notice striking differences from websites that use Flash.
But Flash, a dominant Web technology before the advent of smartphones, relies on downloaded add-ins to browsers called plug-ins. Mr. Jobs withheld support for the approach in iPhones and iPads, and railed against it his April 2010 essay "Thoughts on Flash."
Besides citing technical concerns with Flash, Mr. Jobs argued Apple couldn't allow itself to become dependent on Adobe for such critical technology. As a result, on Apple's mobile devices, websites that rely on Flash display black boxes where videos or graphics should appear.
Adobe rejected Mr. Jobs's arguments, but hedged its bets by developing programming tools that support HTML5 as well as Flash. On Wednesday, it said it would no longer develop new versions of Flash for mobile browsers.
Google has continued to support Flash in the browser delivered with its Android software. But developers want to create Web apps that work both with Android and iOS, Apple's mobile operating system, says Danny Winokur, Adobe's general manager for interactive development.
"If you want to be delivering a Web experience around multiple devices, you have to be doing it in HTML5," he says.
HTML5 takes its name from hypertext markup language, the standard commands used to create Web pages. But the term is a catchall for multiple techniques to handle elements like typography, graphics and video, creating an app-like experience.
"When you show people HTML5 applications, they say that doesn't feel at all like a website," says Dean Hachamovitch, the corporate vice president in charge of Microsoft's Internet Explorer browser.
The technology is equally important for companies to play snazzy-looking ads in mobile apps, says James Lamberti, a vice president at InMobi Mobile Insights, which places ads on mobile devices. He says that major advertisers using its services swelled to 250 in September from 62 in January. "If they are doing rich-media ads, they are doing HTML5."
Then there are Flash-based games that haven't been available on the iPhone and iPad, such as popular titles from Zynga Inc., that work with Facebook Inc's social network. The San Francisco company recently announced three HTML5-based games that work on the Apple devices, exploiting a new Facebook mobile app platform that supports the technology.
Interest from game developers was apparent last week at New Game 2011, a technical conference in San Francisco. Though HTML5 games don't match the graphics and fast action of PC and console games, attendees noted, free social games on the Web are attracting users.
"The real thing you are competing for now is not dollars but the users' time," says Richard Hilleman, chief creative director for game maker Electronic Arts Inc. "So I need to be everywhere they are, and on all the devices that they have."
A shift to HTML5 games that work on many devices, in theory at least, could reduce one of Apple's advantages—the thousands of apps that work only with its hardware specifically.
Cadir Lee, Zynga's chief technology officer, predicts companies will keep tailoring apps for hit devices like Apple's for some time. Yet he thinks HTML5 could eventually evolve to be an even broader technology movement, like that created with websites that could display almost any content. "There is another wave of that revolution that is coming," Mr. Lee says.