Bun is a modern JavaScript runtime built from scratch in Zig that offers significant performance improvements over Node.js. Unlike Node's architecture from 2009, Bun uses Apple's JavaScriptCore engine and makes direct system calls, removing abstraction layers. It includes built-in APIs for common tasks like SQL, S3, Redis, and hashing without requiring npm packages. Running Next.js with Bun is simple—just add 'bun run --bun' to your dev command. Bun also provides a faster package manager (17x faster than Yarn), bundler, and test runner. Native Vercel support is coming soon, though you can already deploy to platforms like Render and Railway. The runtime maintains 100% Node compatibility while delivering better startup times and resource efficiency for modern serverless and development workflows.