nextjs-15

Server Actions in Next.js 15 enable secure server-side mutations directly within React components. You define async functions to handle form submissions, leveraging server components to process data without needing separate API endpoints.

Parallel data fetching in Next.js 15 executes multiple requests concurrently to reduce wait times, while streaming data fetching sends UI chunks to the client progressively using React Suspense to display content as it becomes ready.

Use loading.tsx to display immediate fallback UI during server-side data fetching or route transitions, and use error.tsx to gracefully catch and handle unexpected runtime errors within specific route segments of your Next.js application.

Yes, Route Handlers in Next.js 15 allow you to define and manage backend API endpoints directly within your application directory. They provide a structured way to handle requests and return responses using standard Web APIs.

Middleware in Next.js 15 intercepts incoming requests to execute logic like authentication or redirection before rendering completes. Dynamic metadata is then generated separately within server components to optimize SEO output per route.