What is VAST (video ad serving template)?

A VAST tag is a URL that returns an XML file. The publisher pastes it into the settings of their video player; when a video starts, the player requests the tag, gets the ad’s video file, click-through URL and tracking pixels, and plays the ad as a pre-roll, mid-roll or post-roll.

Because it is a shared standard, one player works with many ad networks, and a network can serve ads into any compatible player. The tracking events (impression, start, quartiles, complete, skip, click) are what the network uses to count and bill CPM.

For tube and video sites, VAST is usually the best paying ad format, since the ad runs inside the player instead of around the page. Check that your player supports the VAST version the network uses and set a sensible skip delay and frequency.