This episode of "How I Built This" interviews Niklas Zennström, co-founder of Kazaa and Skype, about his entrepreneurial journey. The interview traces his career from a corporate job to founding Kazaa (a peer-to-peer file-sharing platform), navigating legal battles, and ultimately creating the hugely successful Skype. Zennström discusses the challenges of bootstrapping, securing funding, and dealing with lawsuits, highlighting the pivotal role of his partnership with Janus Friis. The episode concludes with reflections on the sale of Skype to eBay and Microsoft, and his subsequent venture capital work. A key takeaway is Zennström's emphasis on speed and adaptability in the face of competition and legal challenges.