Apple CEO Steve Jobs holds up an Apple iPhone at the MacWorld Conference in San Francisco, in this Jan. 9, 2007 file photo.
Steve Jobs, the mastermind behind Apple's iPhone, iPad, iPod, iMac and iTunes, has died, Apple said. Jobs was 56.
Apple did not reveal where Jobs died or from what cause -- though he has endured a battle with pancreatic cancer in recent years.
"We are deeply saddened to announce that Steve Jobs passed away today," read a statement by Apple's board of directors. "Steve's brilliance, passion and energy were the source of countless innovations that enrich and improve all of our lives. The world is immeasurably better because of Steve. His greatest love was for his wife, Laurene, and his family. Our hearts go out to them and to all who were touched by his extraordinary gifts."
The homepage of Apple's website this evening switched to a full-page image of Jobs with the text, "Steve Jobs 1955-2011."
Clicking on the image revealed the additional text: "Apple has lost a visionary and creative genius, and the world has lost an amazing human being. Those of us who have been fortunate enough to know and work with Steve have lost a dear friend and an inspiring mentor. Steve leaves behind a company that only he could have built, and his spirit will forever be the foundation of Apple."
Jobs co-founded Apple Computer in 1976 and, with his childhood friend Steve Wozniak, marketed what was considered the world's first personal computer, the Apple II.
Shortly after learning of Jobs' death, Wozniak told ABC News, "I'm shocked and disturbed."
Industry watchers called him a master innovator -- perhaps on a par with Thomas Edison -- changing the worlds of computing, recorded music and communications.
In 2004, he beat back an unusual form of pancreatic cancer, and in 2009 he was forced to get a liver transplant. After several years of failing health, Jobs announced on Aug. 24, 2011 that he was stepping down as Apple's chief executive.
"I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple's CEO, I would be the first to let you know," Jobs wrote in his letter of resignation. "Unfortunately, that day has come."
One of the world's most famous CEOs, Jobs remained stubbornly private about his personal life, refusing interviews and shielding his wife and their children from public view.
"He's never been a media person," said industry analyst Tim Bajarin, president of Creative Strategies, after Jobs resigned. "He's granted interviews in the context of product launches, when it benefits Apple, but you never see him talk about himself."
The highlights of Jobs's career trajectory are well-known: a prodigy who dropped out of Reed College in Oregon and, at 21, started Apple with Wozniak in his parents' garage. He was a multimillionaire by 25, appeared on the cover of Time magazine at 26, and was ousted at Apple at age 30, in 1984.
In the years that followed, he went into other businesses, founding NeXT computers and, in 1986, buying the computer graphics arm of Lucasfilm, Ltd., which became Pixar Animation Studios.
He was described as an exacting and sometimes fearsome leader, ordering up and rejecting multiple versions of new products until the final version was just right. He said the design and aesthetics of a device were as important as the hardware and software inside.