Bill Gates (born October 28, 1955) is an American business magnate, software developer, and philanthropist who co-founded Microsoft in 1975 with Paul Allen. As a pioneer of the microcomputer revolution, he led Microsoft to become the world's largest PC software company. Since 2000, he has focused on philanthropy via the Bill & Melinda Gates Foundation. Bill Gates (born October 28, 1955) is an American business magnate, software developer, and philanthropist who co-founded Microsoft in 1975 with Paul Allen. As a pioneer of the microcomputer revolution, he led Microsoft to become the world's largest PC software company. Since 2000, he has focused on philanthropy via the Bill & Melinda Gates Foundation.