Techniques for displaying advertisements on web pages are provided. A revisitation rate for views of a web page by a user population is determined. A refresh rate for an advertisement space on the web page is synchronized with the determined revisitation rate. An advertisement is selected to be displayed at the advertisement space at a particular refresh time of the synchronized refresh rate. The advertisement is selected based at least on a difference between a content of the web page at the particular refresh time and a content of the web page at a previous refresh time of the synchronized refresh rate.