Which of the following statements about viewability is TRUE?

Viewability is a crucial metric in digital advertising that refers to the standard that ensures ads are actually seen by users. This means that for an ad to be considered "viewable," it must meet specific criteria set forth by industry standards, such as being in the visible portion of a webpage for a certain duration.

The importance of viewability lies in its ability to provide advertisers with confidence that their ads are gaining attention from users, rather than being displayed but not noticed. This standard not only impacts how advertisers measure the success of their campaigns but also influences publishers in terms of the quality and value of their ad inventory.

The other statements are less accurate because viewability is not merely about engagement or interaction; it's a foundational metric in itself that primarily focuses on the visibility of ads, rather than how users behave with them. Additionally, viewability is not optional; it is a key performance indicator commonly used in programmatic advertising to assess the effectiveness of ad placements.