Video Advertising tools enable advertisers to deliver and measure video ad campaigns across devices, and to find and target audiences. Video Advertising describes various video-enabled Display Advertising methods (banner, sidebar, interstitial or overlay), or any video ad served as part of streaming video, video-on-demand, digital subscription and webcasts. Video ads are served as pre-roll units (before the video content begins), mid-roll or post-roll. The term sometimes extends to include Companion ads, the branded "skin" or content surrounding embedded video on any website. Today's feature-rich video marketing platforms enable tracking of ad view counts, how long each viewer let a video play, how many let it play to completion, and how well each video is contributing to sales goals.