Next.js Server Actions allow you to call server-side functions directly from client components. It feels like magic, but it is effectively a modern RPC (Remote Procedure Call) implementation.
The Benefits
1. No Boilerplate: No need to create a file in pages/api, fetch it, parse JSON, and handle errors manually.
2. Type Safety: End-to-end type safety comes for free. The types of arguments and return values are preserved.
3. Progressive Enhancement: They work even if JavaScript is disabled (in some form configurations).
Is it Secure?
Yes, but you must treat them like public API endpoints. Always validate inputs and check authentication inside the action, because a user can send any payload to the underlying URL.