Next.js 16 introduces stable cache components with the use cache directive, completing the partial pre-rendering story. Key updates include Turbopack becoming the default build tool (2-5x faster builds), middleware.ts renamed to proxy.ts, MCP integration for AI agents, and React 19.2 support. The release emphasizes granular caching control through Suspense boundaries and introduces experimental build adapters API for easier deployment to non-Vercel platforms. All routes are now dynamic by default, requiring developers to explicitly cache components.