Which of the following describes the number of times that a unique user will see an ad over a given time period?

Frequency measures the average number of times a unique user sees an ad over a specific period. This is crucial for managing ad exposure and preventing ad fatigue. Reach, while related, refers to the total number of unique users who saw your ad, regardless of how many times they saw it. An impression is a single instance of an ad being displayed, so a user can accumulate multiple impressions. Engagement rate measures user interaction with an ad (e.g., clicks, views), not how many times they saw it.