See also: Transition Ads, Interstitial Ads, Intermercial Ads
CIMM DEFINITION: A preliminary page that precedes the user-requested page of a Web site that usually promotes a particular site feature or provides advertising. (Source: IAB)

Note – A splash page is timed to move on to the requested page after a short period of time or a click. Splash pages are not considered qualified page impressions under current industry guidelines, but they are considered qualified ad impressions. (Source: IAB)