ngIf is the directive. Because it’s a structural directive (template-based), you need to use the * prefix to use it into templates.

*ngIf corresponds to the shortcut for the following syntax (“syntactic sugar”):

<template [ngIf]="condition">
 <p>
    Our heroes are true!
 </p>
</template>

Equivalent to:

<p *ngIf="condition">
  Our heroes are true!
</p>