In Angular 4 you may use ng-template just like ng-container.

The point of this being that the template tag (without the leading ng-) has fallen out of vogue and should not be used. It used to be, in Angular 2, that the template tag and the ng-container tag could both be used when you need a tag that didn't really make a tag in the HTML, sort of an invisible tag, but that only the ng-container tag could use the sugar syntax of *ngFor or *ngIf begging the question "Why care about template tags at all?" and, well, now we are just giving up on the template tags.