Impressions

In online advertising, an impression (also called an ad view) occurs each time an advertisement is fetched from its source and displayed on a user's screen within a webpage or application. Impressions are a fundamental metric for measuring the Reach and visibility of an ad Campaign. It's important to note that an impression means the ad was displayed; it doesn't necessarily mean the user saw or interacted with it. Metrics like Click-Through Rate (CTR) are used to measure engagement with those impressions. Impressions are often bought on a Cost Per Mille (CPM) basis.