What are impressions? Select one option.

Explanation: The correct answer is **The number of times an ad has been displayed on the search engine results page**. Impressions refer to the number of times an ad has been displayed or shown on the search engine results page (SERP) in response to users' search queries. When a user's search query triggers an ad to be eligible for display, but the user doesn't necessarily click on the ad, it still counts as an impression. Impressions serve as a measure of ad visibility and reach, indicating how often an ad has the potential to be seen by users searching for relevant keywords or phrases. Tracking impressions allows advertisers to evaluate the performance and visibility of their ads, assess the effectiveness of their targeting and bidding strategies, and make informed decisions about optimizing their ad campaigns to maximize exposure and engagement. Therefore, in the context of Microsoft Search Advertising, impressions represent the number of times an ad has been displayed on the search engine results page, providing valuable insights into ad visibility and reach.