Understanding the Project Structure

After creating the application, you will see several files and folders. Nest.js provides a predefined structure so you don’t have to organize everything manually.

The most important files are:

• main.ts: starts the application and runs the server;
• app.module.ts: connects all parts of the application;
• app.controller.ts: handles incoming requests;
• app.service.ts: contains business logic.

The application starts from main.ts. This file bootstraps the app and tells Nest to run your server.

The root module defines how your application is structured. It connects controllers and services together.

The controller receives a request and decides what should happen next. It does not contain complex logic.

The service contains the actual logic. It processes data and returns results to the controller.

This separation is one of the key ideas in Nest.js. Each part has a clear responsibility, which makes the application easier to understand and maintain.