Server actions and route handlers

What this means

Server actions run trusted mutations from forms or client calls. Route handlers expose HTTP endpoints when an API-style boundary is appropriate.

In beginner terms, this topic answers one practical question: "What should I write, and why does React care about it?" Do not try to memorize the syntax first. First understand the idea, then connect the syntax to that idea.

Why it matters

Mutations must validate input, check permissions, update data, and refresh affected pages.

When you build real React screens, this idea helps you decide where data should live, what the user should see, and what should happen after an interaction. That is why this lesson is part of the main path instead of being an optional detail.

Step by step

1. Notice the UI problem this topic solves. 2. Look at the smallest possible example. 3. Change one value and predict what should appear. 4. Run the example and compare the result with your prediction. 5. Use the practice task before moving on.

Small example

"use server";

export async function saveLesson(formData) {
  // validate, authorize, save
}

Common mistake

Do not trust roles, ownership, or scores sent by the client.

Practice task

Write the validation and permission steps for publishing a lesson.

Remember this

Every mutation must validate and authorize on the server.