Impressions count how many times your app listing or icon was shown to users across search, browse, and referrals — the top of the ASO funnel before taps and installs.
Impressions measure exposure, not interest. Every time your app appears in search results, a chart, a category, or a referral, that's an impression — whether or not the user taps. Impressions are the denominator of the ASO funnel: from impressions you get product page views (taps), and from those you get installs. Growing impressions is a visibility problem (rankings, featuring, ads); growing the rate at which impressions become installs is a conversion problem (icon, screenshots, ratings).
Reading impressions alongside conversion is what makes them actionable. Rising impressions with flat installs means you're getting seen but not chosen — a conversion fix. Flat impressions with high conversion means the listing works but isn't visible enough — a discovery fix. Apple's App Analytics and the Google Play Console both report impressions so you can diagnose which half of the funnel to work on.
Example
An app sees impressions jump 40% after a ranking win but installs barely move — the data points to a weak first screenshot, not a discovery problem.