Understanding the Use of 'ng-content' Tag in Angular

The 'ng-content' tag in Angular is primarily used for content projection in components. This feature allows developers to define placeholders in a component's template that users can fill with any markup when using the component. Essentially, it helps facilitate parent-child component communication.

For instance, consider a modal component with a dynamic content area. Here's how you can use the 'ng-content' tag:

// Inside the 'modal' component
<div class="modal">
  <h2>Your Modal Window</h2>
  <ng-content></ng-content> <!-- Placeholder for dynamic content -->
</div>

The user of the modal component can then decide what to put inside the modal:

<app-modal>
  <p>This is a dynamic message inside the modal!</p>
</app-modal>

In this case, the 'ng-content' tag acts as a placeholder for any content that needs be projected inside the 'modal' component.

However, it's essential to note that content projection with 'ng-content' does not create a parent-child relationship between the projected content and the component. The projected content remains the child of the component where it's declared, enabling you to maintain a clear hierarchy in your application.

Further, 'ng-content' allows for multiple and selective content projection using the 'select' attribute. It's advantageous when a component needs to receive multiple types of content in different areas of its template.

When utilizing 'ng-content' for content projection, ensure you understand the lifecycle hooks of Angular because the content projection process can affect the timing of these hooks. Also, while 'ng-content' enhances flexibility, avoid overuse as it may lead to complicated dependencies and obscure code - use it judiciously where it provides a clear advantage.

In conclusion, the 'ng-content' tag in Angular opens up powerful options for designing reusable components. This skill is a vital part of advanced Angular development, enabling developers to write more flexible and maintainable code.