Glyphicons is a utility of monochromatic icons and symbols with emphasis on simplicity, keeping usability in mind. The creators of Glyphicons have provided these icons free of cost for Bootstrap. The official Glyphicons web page at http://glyphicons.com/ contains a detailed list of all the icons that are of great use while developing complex websites, as icons are better than words in most cases.
The following screenshot displays some of the popular Glyphicons available for Bootstrap:
Take a look at the following...