What is UI overlay?
An overlay provides contextual information and options in form of an additional layer on top of the current state of the interface. They are either purposefully interruptive like modals or augmenting like popovers and tooltips.
What is an overlay UI UX?
Overlays are handy user interface (UI) components that can simulate interactivity within your design and encourage users to take an important action. Among other things, you can use them for dropdown menus, slide-up keyboards, or lightbox effects.