They are a highly converting and non-disrupting alternative to Popups, because they are not modal.
Fly-Ins are always aligned to an edge of the viewport and do not move while the user scrolls.
A Popup can be displayed once only (for example after a few seconds) or multiple times (for example every time a user clicks on a specific button).
Fly-Ins support all triggers that are available in Divi Areas Pro.
Fly-Ins are often used to collect email addresses (newsletter subscription).
Because they are not modal, users do not find them as distracting as Popups. As a result, people do not close them right away and therefore have a longer exposure time, which in turn increases the conversion rate!
By setting the width of a Fly-In to “100%” (or 100vw) you can easily create a notification bar that spans across the entire width of the browser viewport.