Why did Steve Jobs resign his position as CEO of Apple?

He left from 1985 to 1996 because of differences with his board of directors, and returned as CEO from 1996 to August 2011, two months before his death.

*Jobs was hospitalized frequently after his pancreatic cancer diagnosis in 2003, although he did not die until 8 years later, when it recurred after he received a liver transplant in 2009.