Pre-roll
A pre-roll is a video ad that is played prior to the video that a website visitor actually wants to watch. Often the pre-roll video must be watched in its entirety; sometimes it can be clicked through to the actual video after a few seconds. This form of online advertising is offered by YouTube, among others.
Advertisers pay per view of the preroll ad. Usually they are charged only when the ad video is displayed in full, or from a certain length (for example, 15 or 30 seconds).
The ad video shown may contain a call-to-action, such as visiting a website or buying a product. Usually, while viewing, it is also possible to click through to the advertiser's website. Often it is also possible to combine the pre-roll with displaying banners on the video page.
