SAN FRANCISCO - Apple Inc took a big step toward getting people to store and access their data on the Internet as CEO Steve Jobs emerged from medical leave to present the iCloud music-streaming service.

Apple CEO Steve Jobs talks about the iCloud service at the Apple Worldwide Developers Conference in San Francisco, California, June 6, 2011.[Photo/Agencies]

A thin Jobs walked out on Monday to a standing ovation from the more than 5,000 Apple faithful at its Worldwide Developers' Conference, outlining a service that could further untether users who rely on storing their data on home computers even as they walk around with more and more mobile devices.

Jobs, a pancreatic cancer survivor whose decision to headline the event assuaged some concerns on Wall Street about his health, said nothing about his health, but strode onstage after James Brown's seminal soul classic "I Got You (I Feel Good)" blasted over the sound system.

The Silicon Valley icon touted an Internet-based service for consumers called the iCloud, which lets users play their music and get access to their data from any Apple device -- a crucial capability for users increasingly accustomed to doing things outside their homes.

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"We're going to move the digital hub, the center of your digital life, into the cloud," Jobs said. "Everything happens automatically and there's nothing new to learn. It just all works."

In cloud computing, data and software are stored on servers and devices get access to them through the Internet. Analysts say the iCloud could create a new model for media consumption -- bringing the cloud, which corporations are already familiar with, to many consumer devices.

In an event that held few surprises, Jobs said the iCloud beta version will be available Monday for free. And from the fall, users can pay $24.99 a year to have their song libraries available on iTunes for playback on any Apple gadget.

The feature, which Jobs introduced with his customary "one more thing" phrase toward the presentation's end, catapults Apple past Google Inc and Amazon.com.

Known as iTunes Match, it scans users' hard drives and automatically makes the songs it finds available on the iCloud. In contrast, users of Google and Amazon cloud-based storage have to upload every song themselves.

"This is potentially game changing," said Sterne Agee analyst Shaw Wu. "It's a whole new way of computing where you're less dependent on PCs and local storage."

Apple's adoption of cloud computing "is going to put further pressure on Microsoft," he added.

Pie in the Sky

Monday was only his second appearance in public on the company's behalf since he went on medical leave in January. He shared the spotlight, letting his executive team showcase new features in Apple's mobile and computer operating software.

Attendees and media members walk through the main lobby of the Moscone West Convention Center following the keynote address at the Apple Worldwide Developers Conference in San Francisco June 6, 2011. [Photo/Agencies]

"He is looking thin, but as energetic as usual," Current Analysis analyst Avi Greengart said, adding that Apple's expansion into remote computing "is very powerful stuff."

Apple's move to cloud services comes as the company strives to stay a step ahead of rivals such as Google and Amazon.com in the mobile and online content business.

It could ignite more demand for devices from the iPhone to the iPad, while helping sales of music through iTunes.

More than 25 million iPads sold in the 14 months since the tablet computer was launched, software chief Scott Forstall told the crowd. And customers have bought more than 15 billion songs from iTunes, the world's biggest music store.

Jobs said people will be able to share book purchases, music and data, such as calendar items, across different devices, while backing up and updating information regularly.

Apple will provide five gigabytes of cloud storage -- enough for about 1,000 songs -- for free, but will charge an undisclosed fee in the future for more space.

Apple also introduced software upgrades at the conference, including Lion, its Mac OS X computer operating system and the next version of its mobile operating system.

Apple, legendary for keeping its agenda under wraps, has been unusually open about what it plans to show at its annual developers' conference, a five-day extravaganza for developers who rely on Apple for much of their livelihoods.

Jobs' decision to headline such events often is news in itself after the pancreatic cancer survivor went on his third medical leave for an undisclosed condition.

Apple's share price fell 1.57 percent to close at $341.60 on the Nasdaq stock market. The stock traditionally gains before a major event before dipping on the day it happens.

"They telegraphed in advance what they were going to say and that Steve Jobs was going to show up," said Daniel Ernst at Hudson Square Research. "It's pretty boring, which is, for Apple, bad. It's all good, but everybody always expects them to walk on water unfortunately."