Jobs, who has battled pancreatic cancer and received a liver transplant, has been on medical leave since January of this year. Apple chief operating officer Tim Cook has filled in for him; Jobs, in his note, recommended Cook for the position permanently.

Here's the full text of Jobs's letter.

To the Apple Board of Directors and the Apple Community:

I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple's CEO, I would be the first to let you know. Unfortunately, that day has come.

I hereby resign as CEO of Apple. I would like to serve, if the Board sees fit, as Chairman of the Board, director and Apple employee.