Jobs provided details of Apple's new operating system, Mac OS X, which will ship in the middle of this year. It boasts an interface called Aqua which makes extensive use of colour.
There is also a built-in e-mail facility and an application called the Dock, similar to the Windows Taskbar. From January 2001, OS X will come preloaded on all Macintosh systems.
Jobs co-founded Apple Computer in 1976, but left in 1984 to set up NeXT Software. In 1986 he jointly established Pixar, the animation studio which produced Toy Story and A Bug's Life.
Jobs returned to Apple in December 1996 when Apple bought NeXT. He became interim CEO of Apple in September 1997 after then-CEO Gil Amelio was ousted. He remains CEO of Pixar.
Mac supporters cheered the news. Jobs was the business brain behind Apple's success in the 1980s. When he rejoined, he turned an $878m (£534m) loss in 1997 into a $414m profit in 1998 following the launch of iMac and Power Mac G3 ranges.