The ng-content directive is used to project content into a component from the outside. This allows for more flexibility in component design and reduces the need for nested components.

By using ng-content, you can create more reusable components that can be used in a variety of contexts. For example, instead of creating a component that includes a button and a label, you can create a component that includes ng-content for the label and ng-content for the button. This allows the component to be used with any label and button content, reducing the need for multiple similar components.

<app-button>
  <span>Click me!</span>
  <i class="fa fa-arrow-right"></i>
</app-button>

// app-button component
<button>
  <ng-content select="span"></ng-content>
  <ng-content select="i"></ng-content>
</button>

In the above example, the app-button component includes ng-content for the label and the icon. This allows the component to be used with any label and icon content, reducing the need for multiple similar components.