How to reuse template HTML block in Angular?

I think you wanted to reuse the same html block again. If i understand you correctly, below code should help

<ng-template #MsgRef >
        {{ mycontent }}
</ng-template>

To reuse above block in the same template,

 <ng-template [ngTemplateOutlet]="MsgRef"></ng-template> //reuse any number of times

Creating a new component is the most common way, but sometimes you only need some local markup to be repeated and ng-template allows that.

What is interesting is that it's even possible to pass a context to be able to use data binding:

<ng-template #tplPerson let-person>
    <span class="person-id">{{person.id}}</span>
    <span class="person-alias" *ngIf="!!person.alias">"{{person.alias}}"</span>
    <span class="person-name">{{person.name}}</span>
</ng-template>

let-person without a value defines the context variable person with the value set to $implicit when instantiating the template:

<ng-template *ngTemplateOutlet="tplPerson; context: {$implicit: thePerson}"></ng-template>

See more options in the documentation of NgTemplateOutlet.

I might be late to the party. There are some answers though, but I couldn't achieve it with what is described in above answers I still felt that someone might need a bit of direction.

Key points that are not defined in any of the answers clearly.

1. Consider you have a template which is binding some values in it. So you have to attach a context object in order make template binding work.

<ng-template #invoicesTemplate let-paymentInvoices="paymentInvoices">
    ...
</ng-template>

in usage

<ng-template *ngTemplateOutlet="invoicesTemplate; context: {paymentInvoices : paymentInvoices} "></ng-template>

2. You have to define template first and then use it anywhere you want to. Just think of a function declaration. But until unless you don't call function it wont have any affect.

Overall code declaration of template

<ng-template #invoicesTemplate let-paymentInvoices="paymentInvoices">
  <div class="row">
    <div class="col-sm-12">
      <div class="tags-group">
        <div class="tag" *ngFor="let invoice of paymentInvoices">
          <div class="tag-body">
            <span>{{invoice.invoiceNo }}</span>
            <span (click)="removeInvoice(invoice)"><i title="remove" >x</i></span>
          </div>
        </div>
      </div>
    </div>
  </div>
</ng-template>

calling/usage

<ng-template *ngTemplateOutlet="invoicesTemplate; context: {paymentInvoices : paymentInvoices} "></ng-template>

You can use it any number of times you want.