The co-founder and chief executive officer of computer firm Apple Incorporated, Steve Jobs, has resigned due to health problems. He helped build Apple into the world's most valuable technology company after the firm nearly collapsed in the 1990s.

Jobs is known as a perfectionist, obsessively focused on making products that are easy to use and stylish. He is also known for taking business risks, and learning lessons from products that failed. Several news reports credit Jobs for creating gadgets that customers did not know they needed, and then convincing large numbers of them to pay premium prices for these Apple products.

Apple said Jobs brought “extraordinary vision and leadership” to the company and elected him chairman of the board of directors. In a resignation letter Wednesday, Jobs said he could no longer meet the “duties and expectations” of the CEO position but wished to remain chairman of the board of directors. He has been fighting pancreatic cancer since 2003, received a liver transplant in 2009, and has been on medical leave since January. Apple's share price declined after the announcement, but losses moderated in Thursday's trading.

Tim Cook is Apple's new top executive and has been serving as the company's chief operating officer. Cook has been with Apple for 13 years and is a skilled business executive who streamlined Apple's logistics and improved the way products moved to customers.