Understanding the 'ng-template' Directive in Angular

In Angular, the 'ng-template' directive serves an important purpose: it's primarily used to define the templates that can work in conjunction with structural directives. It essentially provides a mechanism for developers to write HTML that is not rendered directly to the Document Object Model (DOM) but can be referenced and rendered as required.

Let's understand this better with an example. Suppose you want to conditionally render a block of HTML in your Angular application. You can do this using the *ngIf structural directive together with the ng-template directive.

<ng-template [ngIf]="condition">
  <p>This content will only be displayed if the condition is true.</p>
</ng-template>

In the code snippet above, the paragraph tag wrapped inside the ng-template is not displayed directly to the DOM. Instead, it's displayed only when the condition inside ngIf evaluates to true.

If you think about it, the ng-template directive is an integral part of creating dynamic and interactive web applications with Angular, as it conveniently allows for conditional rendering.

However, remember that ng-template is not meant for injecting external HTML content or creating reusable components - Angular has other uniform measures in for these, such as Content Projection for injecting HTML and Angular Components for creating reusable components. Also, ng-template has no role in handling form submissions.

In terms of best practices, it's recommended to keep your ng-template sections as clean and as lean as possible, ensuring that you only include the minimum required HTML and any associated logic within them – this can aid in enhancing your application’s performance.

So, to sum up, the ng-template directive in Angular is a handy tool aimed at defining templates for usage with structural directives, enabling developers to control, streamline, and optimize how their application renders HTML. It's one of the many features of Angular that mirrors the framework's flexibility and dominance in building robust web applications.