Steven P. Jobs, the Apple Inc. chairman and co-founder who pioneered the personal-computer industry and changed the way people think about technology, died Wednesday at the age of 56.

His family, in a statement released by Apple, said Mr. Jobs "died peacefully today surrounded by his family."

The company didn't specify the cause of death. Mr. Jobs had battled pancreatic cancer and several years ago received a liver transplant. In August, Mr. Jobs stepped down as chief executive, handing the reins to longtime deputy Tim Cook.

During his more than three-decade career, Mr. Jobs transformed Silicon Valley as he helped turn the once-sleepy expanse of fruit orchards into the technology industry's innovation center. In addition to laying the groundwork for the industry alongside others like Microsoft Corp. co-founder Bill Gates, Mr. Jobs proved the appeal of well-designed products over the power of technology itself and transformed the way people interact with technology.