The way an ad is shown to the users on your site. For example, an ad may be displayed within the content of your page (e.g. text and display ads), displayed over the top of your page (e.g. anchor ads), etc.
Different ad formats can support different ad types, such as text, display, video, etc. Ad formats may also vary in the number of individual ads they display. For example, the banner ad format will display up to two ads horizontally across the page and the skyscraper will display up to four ads vertically.