Font Awesome provides a set of vector icons and social logos for your website. It is one of the most popular icon sets available.
You can see an example of the use of Font Awesome in the icons shown on Admin > Catalog > Categories/Products:
The pencil, trash can, dollar sign and asterisk are icons from Font-Awesome.
Font Awesome 4.7 is included in Zen Cart 1.5.5 and above.