Badges are used to add extra information to content and are created by using badge Bootstrap span class along with a contextual class (for example, badge-success) on an <span> element.

The numbers (15, 10, and 5) are the badges.
Use the .badge class within <span> elements to create badges:

Example

<a href="#">Questions <span class="badge">15</span></a><br>
<a href="#">Articles <span class="badge">10</span></a><br>
<a href="#">Tutorials <span class="badge">5</span></a>

The following example code shows how to add badges to buttons:

Example

<button type="button" class="btn btn-primary">Slightbook <span class="badge">21</span></button>