Musk co-founded Zip2, a city guide software company, which was sold to Compaq for nearly $300 million in 1999. He then founded X.com, an online payment company, which later became PayPal and was acquired by eBay for $1.5 billion in 2002. With the proceeds from these ventures, Musk founded SpaceX in 2002 with the goal of reducing space transportation costs and enabling the colonization of Mars. SpaceX has since developed the Falcon and Starship rockets, achieving significant milestones in space exploration.