Apple's introduction of the Macintosh in 1984 introduced the graphical user interface to mainstream desktop computing. The Mac ran on a 32-bit processor (compared to 16-bit processors for other PCs at the time) and had 128K of memory, expandable to 192K. It was an immediate success: more than 400,000 Macintosh computers were sold in the first year.
In 1985, Jobs and John Sculley, Apple's president and CEO at the time, clashed over differences about running the company, resulting in Jobs being ousted. He left the company he had co-founded with a net worth of $150 million and started his next venture, Next Computer, which was only moderately successful but planted the seeds for future Apple hardware and software.
In addition to starting Next, Jobs bought feature animation company Pixar in 1986 for $10 million from George Lucas. Since then it has created five of the most successful English-language animation films of all time: "Monsters, Inc." (2001), "Finding Nemo" (2003), "The Incredibles" (2004), "Up" (2009), and "Toy Story 3" (2010). Pixar also collected more than 100 awards and nominations for animated films, commercials and technical contributions.
In 1996 Jobs returned to Apple after it bought Next Computer. He was named interim CEO in 1997 and set about reviving the financially strapped company. Jobs took Apple into the music business with the iPod in 2001 and the iTunes Music Store two years later.
That same year he announced the PowerMac G5, the first 64-bit desktop computer, trumping Intel, AMD and their PC-making partners in the process.
In 2005, at Apple's Worldwide Developer Conference, Jobs said the company would enter the world of Intel processors. A year later it followed through on that pledge, releasing the MacBook Pro and iMac. By August, the company had transitioned fully to Macs using Intel chips.
At Macworld in early January 2007, Jobs showed off the first iPhone and Apple TV, followed the next month by word that the company would offer music free of DRM (digital rights management) at the iTunes Store.
But Jobs' health increasingly took center stage when he appeared in public. By 2006 he was already noticeably thinner, and after his 2008 Macworld keynote, with observers speculating about his health, Apple was forced to react. It said Jobs was suffering from a "common bug" and taking antibiotics for it. Jobs and others said his health issues were "not life-threatening" and did not involve a recurrence of pancreatic cancer.
Later that year Bloomberg posted Jobs' obituary to its newswire by accident (news outlets often have obituaries for elderly public figures -- or those known to be unwell -- written and ready to run.) Although the story was missing a date and cause of death, it fired up more speculation about his health and generated speculative stories about a future at Apple without Jobs.
In January 2009 Jobs, who was always unwilling to share private details of his life, said in a letter that a hormone imbalance had been causing his noticeable weight loss. Just a week or two later he said he would be taking a six-month leave of absence from Apple to deal with his medical condition, which he said had worsened. Cook, who was then COO, handled day to day operations in Jobs' absence. It was revealed later that Jobs had undergone a liver transplant while on hiatus.