Steve Jobs, who, the co-founder of Apple Inc, one of the world''s great entrepreneurs died on Wednesday at the age of 56 after a years-long battle with pancreatic cancer.

His death was announced by Apple and sparked an immediate outpouring of sadness and sympathy from world leaders, competitors and other businessmen including Microsoft co-founder Bill Gates and Facebook CEO Mark Zuckerberg.

The Silicon Valley icon who gave the world the iPod, iPhone and iPad had stepped down as chief executive of the world's largest technology company in August, handing the reins to long-time lieutenant Tim Cook.

He was deemed the heart and soul of a company that rivals Exxon Mobil as the most valuable in America.

"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," Apple said in a statement.

"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."

Apple paid homage to their visionary leader by changing their website to a big black-and-white photograph of him with the caption "Steve Jobs: 1955-2011." The flags outside the company's headquarters at 1 Infinite Loop flew at half mast.

In past years, even board members have confided to friends their concern that Jobs, in his quest for privacy, was not being forthcoming enough with directors about the true condition of his health.

Now, despite much investor confidence in Cook, who has stood in for his boss during three leaves of absence, there remain concerns about whether Apple would stay a creative force to be reckoned with in the longer term without its visionary.

Jobs died one day after the consumer electronics powerhouse unveiled its latest iPhone, the gadget that transformed mobile communications and catapulted Apple to the highest echelons of the tech world.

His death triggered an immediate outpouring of sympathy.

"The world rarely sees someone who has had the profound impact Steve has had, the effects of which will be felt for many generations to come," Gates said. "For those of us lucky enough to get to work with him, it's been an insanely great honor. I will miss Steve immensely."

Outside an Apple store in New York, mourners laid candles, bouquets of flowers, an apple and an iPod Touch in a makeshift memorial.

"I think half the world found out about his death on an Apple device," said Robbie Sokolowsky, 32, an employee for an online marketing company, who lit a candle outside the store.