It’s the measurement layer for your store presence. It brings downloads, rankings, revenue, and conversion together across Apple Ads, the App Store, and Google Play Store, so a change in any one of them shows up next to the others instead of in a separate tool. That's what makes it answer the questions that actually matter: what changed, when it changed, and what likely caused it, whether that was a metadata update, a campaign shift, or the season doing its work.