Font Awesome

You can use a set of 100+ Font Awesome Icons

<i class="fa fa-heart" aria-hidden="true"></i>

Result:    

 fa-adjust  fa-adn  fa-align-center  fa-align-justify  fa-align-left  fa-align-right  fa-anchor  fa-android  fa-angellist  fa-angle-double-down  fa-angle-double-left  fa-angle-double-right  fa-angle-double-up  fa-apple  fa-archive  fa-area-chart  fa-barcode  fa-bars  fa-bicycle  fa-bell-o  fa-bell-slash-o  fa-bookmark-o  fa-bullhorn  fa-bullseye