If a unique user sees an ad over a given time period, what term can be used to describe the number of times that user saw the ad?

Frequency refers to the average number of times a unique user sees an ad over a specific period. It's a key metric for understanding ad exposure and preventing ad fatigue. Engagement rate measures user interaction with an ad (clicks, views, etc.), not the number of times it was seen. Reach is the total number of unique users who saw an ad, not how many times each saw it. An impression is a single instance of an ad being displayed, but it doesn't specify if it's a unique user or how many times that user saw it.