An exit overlay is a modal overlay that activates in the same window the user was browsing in, not a new window like a traditional popup.
It’s a marketing tool designed to convert abandoning web visitors into leads, sales & signups.
Exit overlays grey out the rest of the site in order to focus attention on one specific offer—usually a coupon, discount, or email signup in exchange for an ebook or other publication.
Exit overlays exist for one reason: to sweeten the pot for abandoning users, and recover value from them before they leave your site.
Since much of the work is automated, exit overlays are a way to reduce site abandonment without taking up too much time.
For a full breakdown on what exit overlays are and how they work, we urge you to check out What Are Exit Overlays, And How Do They Work? on the Rooster Blog.