Glossary
Overlay ad
An ad layer that opens on top of the page and blocks it until closed or acted on. Used for exit offers, subscriptions and content locking. Aggressive, cheap, and banned on the platforms that care about experience.
Also called: popover, lightbox ad.
The overlay appears on load, on scroll or when the mouse heads for the close button. Behind it the page dims. It converts because it is impossible to ignore, and it annoys for the same reason.
The related formats are popups (a new window in front), popunders (a new window behind) and interstitials (a full-screen ad between two pages).
Related terms: Popup, Popunder, Content locker.