Angular and the component method for developing modern web applications

Angular components are similar to web components; they are used to compose web pages, or even other components. There can be dozens of components in a web application.

Components define views and templates, and they belong to a module within an application; every application has, at the very least, a root module, named by the Angular CLI as AppModule.ts.

The app.module.ts file contains all of the bootstrap code and configurations for an Angular application, as you can see in the following block of code:

import { NgModule } from '@angular/core';

@NgModule({
  declarations: [
    AppComponent
  ],
  imports: [],
  providers: [],
  bootstrap: [AppComponent]
})
export class AppModule { }

The preceding code is the most basic configuration of an Angular application; we import the NgModule from the Angular core library and use it as a decorator: @NgModule. 

Both components and services are simply classes, with decorators that mark their types and provide metadata that tells Angular how to use them.