William Henry Gates III KBE (born October 28, 1955) is an American business magnate, investor, author, philanthropist, humanitarian, and principal founder of Microsoft Corporation. During his career at Microsoft, Gates held the positions of chairman, CEO and chief software architect. Later in his career and since leaving Microsoft, Gates pursued a number of philanthropic endeavors. In 2009, Gates and Warren Buffett founded The Giving Pledge, whereby they and other billionaires pledge to give at least half of their wealth to philanthropy. The foundation works to save lives and improve global health, and is working with Rotary International to eliminate polio.