Elon Musk had a curious childhood and a passion for science from a young age. He started his first company, Zip2, at age 24, working 18-hour days and eventually selling it for $500 million. With his earnings, he co-founded X.com which later became PayPal, and became the youngest billionaire at age 31 when the company was sold. Musk then founded SpaceX with the goal of establishing a colony on Mars and making humanity multi-planetary, and Tesla Motors to accelerate the world's transition to sustainable energy. He continues working to change the world through technological innovation.