Angular Modules

import { NgModule } from '@angular/core';
import { BrowserModule } from '@angular/platform-browser';
import { FormsModule } from '@angular/forms';
import { AppRoutingModule } from './app-routing.module';
import { AppComponent } from './app.component';

@NgModule({
  declarations: [
    AppComponent    // Components, Directives, Pipes that BELONG to this module
  ],
  imports: [
    BrowserModule,  // Other modules this module DEPENDS ON
    FormsModule,
    AppRoutingModule
  ],
  providers: [],   // Services (rarely needed here since services use providedIn:'root')
  bootstrap: [AppComponent] // The ROOT component to launch the app
})
export class AppModule {}

ng g module products --routing
ng g component products/product-list
ng g component products/product-detail
ng g service products/product

import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { ProductsRoutingModule } from './products-routing.module';
import { ProductListComponent } from './product-list/product-list.component';
import { ProductDetailComponent } from './product-detail/product-detail.component';

@NgModule({
  declarations: [ProductListComponent, ProductDetailComponent],
  imports: [CommonModule, ProductsRoutingModule]
})
export class ProductsModule {}

App Structure with Feature Modules:

src/app/
├── auth/
│   ├── auth.module.ts
│   ├── login/
│   └── register/
├── products/
│   ├── products.module.ts
│   ├── product-list/
│   └── product-detail/
├── admin/
│   ├── admin.module.ts
│   └── dashboard/
└── app.module.ts

// shared/shared.module.ts
import { NgModule } from '@angular/core';
import { CommonModule } from '@angular/common';
import { FormsModule, ReactiveFormsModule } from '@angular/forms';
import { ButtonComponent } from './button/button.component';
import { LoadingSpinnerComponent } from './loading-spinner/loading-spinner.component';

@NgModule({
  declarations: [ButtonComponent, LoadingSpinnerComponent],
  imports: [CommonModule, FormsModule, ReactiveFormsModule],
  exports: [
    // Export everything other modules will need
    CommonModule, FormsModule, ReactiveFormsModule,
    ButtonComponent, LoadingSpinnerComponent
  ]
})
export class SharedModule {}

imports: [SharedModule]  // Gets all shared components and modules

// core/core.module.ts
@NgModule({
  declarations: [NavbarComponent, FooterComponent],
  imports: [CommonModule, RouterModule],
  exports: [NavbarComponent, FooterComponent]
})
export class CoreModule {}

const routes: Routes = [
  { path: '', component: HomeComponent },
  {
    path: 'products',
    loadChildren: () => import('./products/products.module').then(m => m.ProductsModule)
  },
  {
    path: 'admin',
    loadChildren: () => import('./admin/admin.module').then(m => m.AdminModule)
  }
];