List of Web Safe Fonts

font-family: Arial, Helvetica, sans-serif;
font-family: 'Arial Black', Gadget, sans-serif;
font-family: 'Bookman Old Style', serif;
font-family: 'Comic Sans MS', cursive;
font-family: Courier, monospace;
font-family: 'Courier New', Courier, monospace;
font-family: Garamond, serif;
font-family: Georgia, serif;
font-family: Impact, Charcoal, sans-serif;
font-family: 'Lucida Console', Monaco, monospace;
font-family: 'Lucida Sans Unicode', 'Lucida Grande', sans-serif;
font-family: 'MS Sans Serif', Geneva, sans-serif;
font-family: 'MS Serif', 'New York', sans-serif;
font-family: 'Palatino Linotype', 'Book Antiqua', Palatino, serif;
font-family: Symbol, sans-serif;
font-family: Tahoma, Geneva, sans-serif;
font-family: 'Times New Roman', Times, serif;
font-family: 'Trebuchet MS', Helvetica, sans-serif;
font-family: Verdana, Geneva, sans-serif;
font-family: Webdings, sans-serif;
font-family: Wingdings, 'Zapf Dingbats', sans-serif;

Source