The announcement was made at Apple's annual developers' conference in San Francisco. The team unveiled the company's next generation of software, which includes the iCloud.
Jobs looked thin but excited about Apple's newest product.
An iCloud account will store user information from several devices, including iPhones and iPads, and make sure the same contacts, calendar events and files are available on all of them. It also backs up the data on Apple's servers. It mimics Google's Docs system for online files, and products from smaller online-storage companies like Dropbox.
For $25 a year, iTunes will be able to scan a computer's hard drive for music files that have been converted from CDs or come from other sources. If the same songs are available in the iTunes store, they'll be added to the iCloud locker. That means there's no need to purchase the songs again or upload them. The service, known as iTunes Match, will upload any songs to iCloud if it's not already available through iTunes.
The company also announced new software to make Mac computers behave more like mobile devices and Apple's mobile devices more like rival smartphones.
Jobs has been on medical leave since January. He was diagnosed with pancreatic cancer in 2003 and had a liver transplant in 2009. His last public appearance was in March when he announced the iPad 2.
The Associated Press contributed to this story.