No, Nostr (short for "Notes and Other Stuff Transmitted by Relays") is not just for Bitcoin. While Nostr is popular within the Bitcoin community due to its decentralized nature and the integration of Bitcoin-related features like Lightning Network payments, its use case is much broader.

Key Points About Nostr:

1. Protocol, Not an App: Nostr is a decentralized communication protocol. It's not tied to any specific content, making it suitable for various applications like social media, messaging, blogging, and beyond.

2. Decentralization: It emphasizes censorship resistance and decentralization, making it appealing to those in the Bitcoin and Web3 communities, but it's not exclusively for Bitcoin users.

3. Bitcoin Integration: Many Nostr clients and applications incorporate Bitcoin's Lightning Network for microtransactions, tips, or payments, but this is an optional feature.

4. Broader Use Cases: Developers are using Nostr to build:

Decentralized social media platforms (like Damus and others).

Encrypted messaging systems.

Content publishing tools.

Applications for communities interested in censorship-resistant communication.

5. Open to All: Anyone can use Nostr for any purpose, regardless of whether they're involved with Bitcoin or cryptocurrencies.

While Nostr’s adoption may have been driven initially by the Bitcoin community, its capabilities are universal, making it a tool for a wide variety of decentralized and censorship-resistant applications.