- Standard sizes represent regular display ad slots.
- Video sizes represent video players on a page that can show VAST (Video Ad Serving Template) ad responses.
A video ad unit is an ad unit that contains a video size (such as 400x300v). The master video size represents the video player size on the page. You must include the letter "v" at the end of any video size to indicate that it's a video size and capable of playing back videos sent in the VAST format.