Impressions
The number of times an ad is displayed or shown to users, regardless of whether it was clicked or not.
Tags:metricsreachdisplay adsmeasurement
Every time one piece of content is shown to a user (whether it's organic content or ads), it's called an "Impression."
It's called impression because of traditional newspaper advertising. 3000 "impressions" meant your content would be printed in 3000 newspapers.
"Pay per impression" is the main pricing model for most interruption-based platforms like Meta, LinkedIn, Reddit, X, etc (unlike search-based ones like Google, that usually charges per click).
We often use "Cost Per Thousand Impressions" (or CPM) to measure how expensive it is to display your ads 1,000 times.
Impressions are different from Reach. Reach is the number of unique users who saw your ad, while impressions are the number of times your ad was displayed. One person can generate multiple impressions if they see your ad multiple times.