Pop ups are small windows that appear on computer screens while browsing the internet, which can often be disruptive to the user. Synonyms for pop-ups include popovers, overlays, modals, interstitials, and fly-ins. These terms are used in web development to describe various types of pop-up windows that can be used for advertising, subscription forms or surveys. Popovers are similar to pop-ups, but they are designed to be less intrusive by appearing in the corner of a website's page. Overlays, on the other hand, cover a portion of the web page and can be used for authentication or login boxes. Modals are windows that appear in the center of the screen, creating a focus on the content. Interstitials are full-screen ads that can be seen while navigating between pages. Fly-ins allow the display of content from the side or bottom, without taking the entire page.