Apple shares fall as Jobs quits
More than almost any other business leader, Steve Jobs has become indistinguishable from the company he runs.
As the face of Apple, he represents its dedication to high-end technology and fashionable design.
And inside the company he exerts a level of influence unheard of in most businesses.
But while the two seem inseparable, Mr Jobs's 35-year relationship with Apple has endured ups and downs.
The beginnings of Apple go back to 1970s California, where a computer revolution stirred in offices and schoolrooms up and down Silicon Valley.
Mr Jobs, adopted by a local couple in 1955, found himself growing up in the heartland of a hi-tech revolution.
He was talented academically, but had few friends until meeting local computer whizkid Steve Wozniak in the early 1970s.
The duo worked together on a handful of pet projects, before eventually linking up to launch a new computer company, Apple.
The business became a success almost as soon as it was founded in 1976. Mr Wozniak's innovative designs meant users could extract maximum power from their machines, allowing them to achieve things that were impossible on other systems.
As the standard bearer for an army of young, dynamic computer manufacturers bursting out of the Silicon Valley hothouse, investors and the press couldn't get enough of Apple.
Shares in the company were in such high demand that by the time it opted for a flotation in 1980, it became the biggest stock market launch since Ford in 1956.Demanding reputation
Meanwhile, Steve Jobs had built a reputation as a forthright and demanding leader who could take niche technologies - such as the mouse and the graphical window-based interface - and make them popular with the general public.
But his lack of business experience meant that boardroom decisions were left in the hands of others - not all of whom felt he was a good influence.
Eventually it turned to conflict and, after a bust-up with chief executive John Sculley in 1985, he quit the company that made him rich.
Never one to dwell on the past, Jobs got back into the action almost immediately.
He bought fledgling computer animation studio Pixar and founded NeXT, a computer maker that built the sort of high-end products he had championed at Apple.
Meanwhile, his former company's shine began to wear off under pressure from the ever-expanding empire of Bill Gates's Microsoft until, in 1996 - more than a decade after casting Steve Jobs into the wilderness - it turned back to him for help.
Looking for a software strategy to help it take on Microsoft, Apple bought NeXT for more than $400m.
The move was a gamble, but it brought Mr Jobs back into the fold, much to the excitement of the company's followers. He soon stepped in to replace under-fire chief executive Gil Amelio, rallying the faithful and promising to revitalise the company.Third act
Almost immediately, he made his impact felt. Scrapping a whole range of products that he deemed superfluous to requirements, Mr Jobs targeted just a handful of ideas that he thought would help return Apple to success.
The first, the colourful iMac computer, sold well and brought back some of the cool factor that had driven the company to its heights in the 1980s - but it was Jobs's intention to take Apple beyond the desktop computer that really sealed the firm's comeback and underscored his reputation as an innovator.
In 2002 the company launched the iPod, a chunky music player that went on to sell more than 250m units worldwide.
That hit, in turn, sparked the launch of the iTunes Store, a music download service that radically altered the market and went on to become the world's biggest music retailer.
Jobs followed that up with two more hits, the iPhone in 2007 and the iPad in 2010, which have both expanded the idea of what a computer could be.
Since returning to Apple, everything he touches seems to turn to gold. Even Pixar's sale to Disney in 2006 for $7.4bn (£4.6bn) increased his power and left him the biggest shareholder in the American entertainment giant.
Famed for public appearances in which he wears his trademark black turtle neck and blue jeans, admirers put Mr Jobs's success down to his dedication to perfection.
He runs Apple with an iron fist and dictates even the smallest details about the company's products and strategy, translating his own personal values as a Buddhist and strict vegan into sleek, minimalist products.
Despite a high profile, however, he has remained fiercely protective of his private life. He married his wife Lisa in 1991, and the couple have three children. Mr Jobs also has a daughter from a previous relationship, and as an adult discovered that he had a biological sister, US novelist Mona Simpson.
For all his success, however, there is one area of his life that Mr Jobs has been unable to control: his health.
In 2004 it was announced that he had been diagnosed with a rare form of pancreatic cancer - a fact that was only revealed after he had failed to treat it through unconventional means.
Though the disease was eventually beaten into remission, complications emerged and it later emerged that he underwent a life-saving liver transplant in 2008.
Despite fears that his health may have blunted his ambition, however, those moments seem to have sharpened a business method that often seems wilful, individualistic and counterintuitive.
Perhaps it should be no surprise: in 2005, shortly after his first brush with cancer, he gave a stirring commencement speech to students at Stanford University that revealed that the frailty of life is a driving force behind his approach to life and business.
"Remembering that I'll be dead soon is the most important thing I've ever encountered to help me make the big choices in life," he said.
"Remembering that you are going to die is the best way I know to avoid the trap of thinking that you have something to lose. You are already naked. There is no reason not to follow your heart."