Data types: MIME
		¡ Multipurpose Internet Mail Extensions (text/plain, img/jpg application/msword) l Simple format, pre-web l Can code an unofficial type using x-subtype prefix (e.g., audio/x-pn-realaudio) l Application tag: need to use an application to handle this data l Wild success shows a simple system is best: ¡ Good for adoption / authoring ¡ Good for common denominator