What is a NestJS module, and why is it needed?
A module is a class decorated with @Module() that acts as the organizational unit of a NestJS app. It groups related controllers, providers, and imports. Every app has at least one root module (AppModule). NestJS uses the module graph to wire up the DI container at startup.
A module is a class annotated with the @Module() decorator. NestJS uses the information provided by this decorator to organize the application structure and build the dependency injection container.
Key points about modules:
Every NestJS app has at least one root module — AppModule.
Modules encapsulate a closely related set of capabilities.
The module graph is used by NestJS to resolve provider dependencies.
Modules are singletons by default — the same instance is shared across the app.
Basic module example