Bill Gates, born William Henry Gates III on October 28, 1955, is an American businessman, investor, philanthropist, and writer. He is best known for software giant Microsoft alongside his childhood friend Paul Allen. During his tenure at Microsoft, Gates held various key positions, including chairman, and chief executive officer (CEO). Gates was a pioneer of the microcomputer revolution during the 1970s and 1980s. In June 2008, Gates transitioned into a part-time role at Microsoft and focused on full-time work at the Bill & Melinda Gates Foundation.