In a regular HTML-based webpage, from the time the webpage is loaded in the browser and every time a user clicks on a link, a page is loaded and a new impression is made on the ads. When your business is online and part of your revenues come from ad-impression and earnings per leads, every time a webpage is refreshed means a new impression and eventual revenue in your end. Online companies, for example Google offers incentives for web creators and administrators for ad impressions. Small online advertising companies seek out different popular websites and pay not only per lead but also per impression.