Answer - Alternate Style Sheet is a sheet defining an alternate style to be used in place of style(s) declared as persistent and/or preferred . Persistent style is a default style that applies when style sheets are enabled but can disabled in favor of an alternate style, e.g.: Preferred style is a default style that applies automatically and is declared by setting the TITLE attribute to the LINK element. There can only be one preferred style, e.g.: Alternate style gives an user the choice of selecting an alternative style - a very convenient way of specifying a media dependent style. Note: Each group of alternate styles must have unique TITLE, e.g.: Alternate stylesheet are not yet supported.