Google Ads terms: I 3 terms, defined.

One showing of an ad. An impression costs nothing on a cost-per-click campaign: you pay when someone clicks.

The share of searches your ads showed on, out of all the searches they were eligible for. What is missing is split between lost to budget and lost to rank.

The part of a result that would not have happened without the ad. Brand searches often have low incrementality, because people searching your name were already coming.