since different fonts comes installed on different systems and with different programs, there's actually very few fonts that are truly web safe. Best one can hope for really is commonly installed fonts and then suggest reasonable fallbacks. this work for fonts like Verdana and Arial where the fall back fonts and eventually the default system font for the browser really doesn't change the look of the page drastically. but for special case fonts like a specific "sarcasm font" the change of a good fallback on any given system is not very good.
w3 schools has a list of commonly used fonts with fallbacks and families here
http://www.w3schools.com/cssref/css_websafe_fonts.asp you'll find most pages uses one of these.