You can be used as part of links or buttons to provide a counter & as a icon notifications. See the examples.
Detailed documentation and more examples you can find in our Bootstrap Badges Docs
Basic example
Add class .text-center to the parent div to align any item
inside to the center.
Sizes
Badges scale to match the size of the immediate parent element by using relative font sizing and em units. As of v5, badges no longer have focus or hover styles for links.