Who is Sean Parker from The Accidental Billionaires: The Founding of Facebook: A Tale of Sex, Money, Genius and Betrayal and what is their importance?

Sean Parker was already a big fish in a small pond when Zuckerberg met him. Parker had created a site called Napster, which allowed people to download music from their favorite artists. Sean and Mark became friends, and they took Facebook to the next level after Saverin left the team. He went onto serve as the president of Facebook.