Stay On is a rich media ad unit which appears at the bottom of the browser. While many ad formats can be disturbing to visitors, Stay On is widely used because the ads are visible without being intrusive. Research has shown that because of this, the visitor tends to focus on the ad message rather than the inconvenience.
They slide into place after a webpage is opened, and stay there as the user scrolls up or down the webpage. Users are given the option to close the ad unit if they wish.