Services in Angular are designed to encapsulate reusable logic, data, and functionality that can be shared across multiple components in the application.

Angular's DI utilizes the Decorator design pattern to inject dependencies into components, services, and other Angular classes.

The providedIn property in Angular services determines the scope of the service, whether it's available throughout the application (root) or only within a specific component (component).

The @Injectable() decorator in Angular is used to mark a class as a service, indicating that it can be injected into other components, services, or modules.

The @Inject() decorator in Angular allows you to specify the dependencies required by a service, enabling DI and the automatic instantiation of those dependencies.

The ngOnDestroy() lifecycle hook method in Angular is called when a service is destroyed, allowing for cleanup tasks and the release of resources.

The providers array in Angular modules is used to define the services that are available within that module, allowing for their injection into components and other services.

The HttpClient service in Angular is used for making HTTP requests and handling HTTP responses, providing a convenient way to communicate with RESTful APIs.

In Angular, singleton services are instantiated once and reused throughout the application, while transient services are created each time they are injected, providing more flexibility and control over the lifecycle of the service.

NgRx Store is a popular state management library for Angular that provides a centralized store for managing application state and data, enabling consistent and predictable state updates across components.

The @Optional() decorator in Angular allows you to specify that a dependency is optional and can be omitted if it is not provided by the DI system, providing flexibility in dependency injection.

The providedIn property in Angular services determines the scope of the service, whether it's available throughout the application (root) or only within a specific component (component).

The @SkipSelf() decorator in Angular allows you to skip the current component and search for the dependency in the parent component, enabling you to access dependencies from higher levels in the component hierarchy.

AuthService is a common name for a service in Angular that handles user authentication and authorization, providing methods for login, logout, and managing user roles and permissions.

The @Host() decorator in Angular allows you to access the host element of a directive, providing a way to interact with the DOM element that the directive is attached to.