Apple's co-founder and former CEO Steve Jobs has died, aged 56.
Steve Jobs battled with pancreatic cancer, requiring him to undergo liver transplant surgery in 2009. The Apple co-founder stepped down as Apple CEO in August 2011 after a second bout of medical leave since the start of the year.
Jobs's successor, Tim Cook, paid tribute to a "visionary and creative genius".
"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," said Cook.
US president Barack Obama said the world had lost a visionary. "Steve was among the greatest of American innovators," said Obama.
Jobs's technology industry peers paid tribute to him via social networking sites, along with hundreds of thousands of people worldwide.
Microsoft's Bill Gates tweeted: "For those of us lucky enough to get to work with Steve, it's been an insanely great honour. I will miss Steve immensely."
Michael Dell, founder and CEO at Dell, said: "Today the world lost a visionary leader, the technology industry lost an iconic legend and I lost a friend and fellow founder."
HP CEO Meg Whitman said: "Steve Jobs was an iconic entrepreneur and businessman whose impact on technology was felt beyond Silicon Valley. He will be remembered for the innovation he brought to market and the inspiration he brought to the world."