What is an app install ad?

Q) What is an app install ad?

Ans:

An ad format for advertisers to re-engage with users who have already downloaded the app.
An app extension which shows a link to your app below your ad.
A templated way to create text, banner, image, and interstitial ads driving users to the Google Play store.
A type of targeting used to match your ads to sites or pages based on the keywords or topics you’ve chosen.