[singold]

About Glyphicons

From Bootstrap docs (http://twitter.github.io/bootstrap/base-css.html#icons):

"Glyphicons Halflings are normally not available for free, but an arrangement between Bootstrap and the Glyphicons creators have made this possible at no cost to you as developers. As a thank you, we ask you to include an optional link back to Glyphicons whenever practical."

[walkon]

Font Awesome's license makes it effectively free:

http://fortawesome.github.io/Font-Awesome/license/

[ZeroGravitas]

The Font Awesome licence is much better (permissive) than the Glyphicons one.