Frequently-used modules

An Angular application needs at least one module that serves as the root module. As you add features to your app, you can add them in modules. The following are frequently used Angular modules with examples of some of the things they contain:

NgModule Import it from Why you use it
BrowserModule @angular/platform-browser To run your application in a browser.
CommonModule @angular/common To use NgIf and NgFor.
FormsModule @angular/forms To build template driven forms (includes NgModel).
ReactiveFormsModule @angular/forms To build reactive forms.
RouterModule @angular/router To use RouterLink, .forRoot(), and .forChild().
HttpClientModule @angular/common/http To communicate with a server using the HTTP protocol.

Importing modules

When you use these Angular modules, import them in AppModule, or your feature module as appropriate, and list them in the @NgModule imports array.

For example, in a new application generated by the Angular CLI, BrowserModule is imported into the AppModule.

import { BrowserModule } from '@angular/platform-browser';
import { NgModule } from '@angular/core';
import { AppComponent } from './app.component';
declarations: [
imports: [
/* add modules here so Angular knows to use them */
providers: [],
bootstrap: [AppComponent]
export class AppModule { }

The imports at the top of the array are JavaScript import statements while the imports array within @NgModule is Angular specific. For more information on the difference, see JavaScript Modules vs. NgModules.

BrowserModule and CommonModule

BrowserModule re-exports CommonModule, which exposes many common directives such as ngIf and ngFor. These directives are available to any module that imports the browser module, given the re-export.

For applications that run in the browser, import BrowserModule in the root AppModule because it provides services that are essential to launch and render your application in browsers.

Note: BrowserModule's providers are for the whole application so it should only be in the root module, not in feature modules. Feature modules only need the common directives in CommonModule; they don't need to re-install app-wide providers.