This document discusses 15 different types of online advertising, including banner ads, text ads, display ads, pop-up ads, flash/DHTML ads, interstitial ads, video ads, email ads, on-site sponsorships, advertorials, floating ads, unicast ads, takeover ads, contextual ads, and pay-per-click ads. Each type is briefly defined and examples are provided. The advantages of internet advertising through pay-per-click are also mentioned.