Understanding the architecture of Angular is crucial for building efficient and scalable applications. Angular is a platform and framework for building single-page client applications using HTML and TypeScript. It implements core and optional functionality as a set of TypeScript libraries that you import into your applications.

• NgModules: Angular applications are modular and use NgModules to organize an application into cohesive blocks of functionality.
  • Root Module: Every Angular application has at least one module, the root module, conventionally named AppModule.
  • Feature Modules: These are additional modules that can be used to organize code into distinct features.

• Components: The building blocks of an Angular application. Each component consists of:
  • Template: Defines the view for the component.
  • Class: Contains the logic and data for the component.
  • Metadata: Provides additional information about the component to Angular.

• Templates: Define the HTML view of a component. They can include Angular directives and binding markup to connect the DOM with the component data.

• Metadata: Used to decorate a class so that it can configure the expected behavior of the class. For example, the @Component decorator is used to define a component.

• Data Binding: Mechanism to coordinate the communication between the component class and the template. There are four types of data binding:
  • Interpolation: {{ expression }}
  • Property Binding: [property]="expression"
  • Event Binding: (event)="handler"
  • Two-Way Binding: [(ngModel)]="property"

• Directives: Classes that add additional behavior to elements in your Angular applications.
  • Structural Directives: Change the DOM layout by adding and removing DOM elements (e.g., *ngIf, *ngFor).
  • Attribute Directives: Change the appearance or behavior of an element, component, or another directive (e.g., ngClass, ngStyle).

• Services: Classes that handle the business logic and data access. They are typically used to share data and functionality across components.
• Dependency Injection (DI): A design pattern used to implement IoC (Inversion of Control), allowing Angular to manage the creation and lifecycle of services.

• Routing: Angular's router enables navigation from one view to the next as users perform application tasks. It maps URL paths to components.

• Observables: Used for handling asynchronous operations. Angular uses the RxJS library to provide a powerful way to work with asynchronous data streams.

An Angular application typically follows a specific structure to maintain organization and scalability. Here is a basic structure of an Angular application:

Let's create a simple Angular component to understand the architecture better.

Use Angular CLI to generate a new component:

The command above creates four files:

• example.component.ts: The component class.
• example.component.html: The component template.
• example.component.css: The component styles.
• example.component.spec.ts: The component test file.

Add the component selector to the app.component.html:

Run the application using the Angular CLI:

Navigate to http://localhost:4200 to see the new component in action.

In this section, we covered the fundamental concepts of Angular architecture, including modules, components, templates, metadata, data binding, directives, services, dependency injection, routing, and observables. We also walked through a practical example of creating a simple component to solidify these concepts. Understanding these core principles is essential for building robust Angular applications. In the next module, we will dive deeper into Angular components and their interactions.