In online advertising engagement metrics are the metrics used to measure consumers' engagement with the ads they encounter online. Engagement metrics are used by digital media buyers to gauge the effectiveness of their advertising. This is most easily done by direct marketers who use CPA buying strategies but there are a variety of other ways to measure the impact of ads via engagement. Some possible engagement metrics include whether a user has watched an entire video ad if a user hovers over a creative with a mouse and whether a user has clicked on an ad. More generally the term engagement metrics may also be applied to a range of online behaviors such as how long a visitor spends on a website.