William Henry Gates III (born 28 October 1955) is an American business magnate, software developer, and philanthropist. He co-founded Microsoft with Paul Allen in 1975, leading it to become the world's largest personal computer software company. He served as chairman, CEO, and chief software architect, and was the largest individual shareholder until 2014. He was the world's richest person for most of the period from 1995 to 2017. In his later career, Gates transitioned to full-time philanthropy, co-founding the Bill & Melinda Gates Foundation. He focuses on global health, climate change, and education. He has donated billions to eradicate polio and malaria. Despite his charitable work, he remains a subject of public scrutiny regarding his business tactics in the 90s and his personal life.