Ejemplos de iconos de distintas fuentes

Iconos de Material

< link href="https://fonts.googleapis.com/icon?family=Material+Icons"> rel="stylesheet"> face face face face

fontawesone

< link rel="stylesheet" href="https://cdnjs.cloudflare.com/ajax/libs/font-awesome/4.7.0/css/font-awesome.min.css">

Used on a button:

Unicode:

Iconos de Boostrap

<link rel="stylesheet" href="https://maxcdn.bootstrapcdn.com/bootstrap/3.3.7/css/bootstrap.min.css">

Thumbs-up icon:

Thumbs-up icon as a link:

Thumbs-up icon on a button:

Thumbs-up icon on a styled link button: Like

Unicode:

En formato svg