Floating Bar
A slim banner pinned to the top or bottom of the viewport that stays visible as the visitor scrolls, holding one line of text and one action.
A floating bar (also called a sticky bar or hello bar) fixes itself to the top or bottom edge of the screen and remains there as the page scrolls. It is narrow enough to leave the content fully visible, which makes it acceptable to show immediately on load where a modal would not be. Google's intrusive interstitial guidance names banners that use a reasonable amount of screen space as an acceptable pattern.
It suits announcements and single-action offers: a free shipping threshold, a launch discount, a webinar signup, or a one-field email form for a guide. Because it is always in view, it works as a standing reminder rather than a one-time interruption, and a visitor can act on it at any point in the session.
Keep it to one message and one button. A bar crowded with two offers and a search field loses the clarity that made it tolerable. Watch layout shift: a top bar that pushes content down after load counts toward Cumulative Layout Shift, one of Google's Core Web Vitals, so reserve space for it or pin it to the bottom instead.
See it in practice