X.com was a domain associated with Elon Musk, the CEO of SpaceX and Tesla. It originally served as the website for his online payment company, X.com, which he founded in 1999. X.com later became PayPal after a merger with Confinity, and in 2001, the name was changed to PayPal, which is now a well-known global online payment system.
However, it's worth noting that domain names and websites can change hands or purposes over time. In July 2023 Elon Musk decided to change the name of Twitter to X.com.