Nostr is a protocol for building censorship-resistant decentralized applications, with social media being an early use case. It uses public/private key pairs like Bitcoin and allows users to subscribe to independently run relay servers. This avoids centralized control and censorship compared to current social platforms that sell user data and determine algorithmically what content users see. Nostr aims to reward users for valuable content and not monetize through advertising. It could provide an open alternative to platforms like Twitter and Substack that have faced censorship controversies.