News Americas, NEW YORK, NY, Thurs. Aug. 25, 2011: Apple founder Steve Jobs has called it quits.

Jobs, 55, who has been on medical leave since January, yesterday resigned as chief executive of the technology giant.

Jobs, who underwent a liver transplant following pancreatic cancer, said he could no longer meet his chief executive’s duties and expectations and was resigning. “I have always said if there ever came a day when I could no longer meet my duties and expectations as Apple’s chief executive, I would be the first to let you know,” he wrote in a short letter to the board. “Unfortunately, that day has come. I hereby resign as chief executive of Apple. I believe Apple’s brightest and most innovative days are ahead of it. And I look forward to watching and contributing to its success in a new role.”

He will become chairman of the firm and is set to be replaced in the top spot by Apple’s chief operating officer, Tim Cook.