HE has steered the firm from no man's land to technological giant, redefining computer, music and mobile phone markets one by one until its products could be found in households worldwide.

But now, however, Apple co-founder Steve Jobs -- who has suffered a prolonged period of ill health and previously underwent a liver transplant after suffering from pancreatic cancer -- stepped down as chief executive, 35 years after launching the company.

His iPhone, iPod and iPad creations, are used by millions of people around the world and revolutionised the computer industry. But, for many, Jobs is the heart and soul of a company that this month briefly became the most valuable in America.

His battle has been of deep concern to Apple fans, investors and the company’s staff. Over the past two years, directors have confided to friends their concerns that Jobs, in his quest for privacy, wasn’t being forthcoming about the true condition of his health.

The 56-year-old college drop-out, Buddhist and a son of adoptive parents, started Apple Computer with friend Steve Wozniak in the late-1970s.

The company soon introduced the Apple 1 computer. But it was the Apple II that became a huge success and made Apple a big player in the then-nascent PC industry, culminating in a 1980 stock market flotation that made Jobs a multi-millionaire.

Despite Apple’s success, Jobs’s relationship with top management and the board soured. The company removed most of his powers and then, in 1985, he was fired.

Apple’s fortunes waned after that. However, its purchase of NeXT -- the computer company Jobs founded after leaving Apple -- in 1997 brought him back into the fold. Later that year, he became interim chief executive, and in 2000 the firm dropped “interim” from his title.

But it was the iPhone in 2007 that cemented his legacy in the annals of modern technology. Two years before the gadget that forever transformed the way people around the world access and use the internet, Jobs said a sense of his own mortality was a major driver behind that vision.

“Remembering that I’ll be dead soon is the most important tool I’ve ever encountered to help me make the big choices in life,” Jobs said in 2005.

“Because almost everything --all external expectations, all pride, all fear of embarrassment or failure -- these things fall away in the face of death, leaving only what is truly important.”

“Remembering you are going to die is the best way I know to avoid the trap of thinking you have something to lose. You are already naked. There’s no reason not to follow your heart.”

Apple’s stock traded down 4.1% in Frankfurt yesterday following a drop of as much as 5% in after-hours trading across the Atlantic, amid warnings billions will be wiped off the company’s value through the loss of its charismatic leader. However, prices were only marginally down when Wall Street opened.

He has been on medical leave for an undisclosed condition since January with his latest decision to take a back seat sparking fears his health may be deteriorating further.

Jobs will take on a new role as chairman as Apple’s chief operating officer, Tim Cook, prepares to become the face of the firm on a permanent basis.

In a letter of resignation addressed to the company’s board and the community of Apple users, Jobs said: “I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple’s chief executive, I would be the first to let you know. Unfortunately, that day has come.

“I believe Apple’s brightest and most innovative days are ahead of it. And I look forward to watching and contributing to its success in a new role. I have made some of the best friends of my life at Apple, and I thank you all for the many years of being able to work alongside you.”

Art Levinson, an Apple director, said Jobs had delivered “countless contributions” to the company’s success. He added: “Steve’s extraordinary vision and leadership saved Apple and guided it to its position as the world’s most innovative and valuable technology company.”

Gus Hamilton, 30, one of the customers at Apple’s store in Buchanan Street, Glasgow, yesterday, said: “It’s bad because Steve Jobs has always been the face of Apple.”