William Henry Bill Gates III (born October 28, 1955)[2] is an American business magnate, philanthropist, and chairman[3] of Microsoft, the software company he founded with Paul Allen. He is ranked consistently one of the world s wealthiest people[4] and the wealthiest overall as of 2009.[1] During his career at Microsoft, Gates held the positions of CEO and chief software architect, and remains the largest individual shareholder with more than 8 percent of the common stock.[5] He has also authored or co-authored several books.