Bootstrap offers over 250 Glyphicon icons for free. As a thank you, they only ask that you include a link back to Glyphicons whenever possible.
How to use Glyphicons
For performance reasons, all icons require a base class and individual icon class. To use, put code about <span>.
for example:
<button type="button" class="btn btn-default" aria-label="Left Align">
<span class="glyphicon glyphicon-align-left" aria-hidden="true"></span>
</button>
<button type="button" class="btn btn-default btn-lg">
<span class="glyphicon glyphicon-star" aria-hidden="true"></span> Star
</button>
Icon classes cannot be directly combined with other components. They should not be used along with other classes on the same element. Instead, add a nested <span> and apply the icon classes to the <span>.
Icon classes should only be used on elements that contain no text content and have no child elements.
There are icons table with the base and individual classes:
