This form of marketing is basically used to increase downloads of any new or old app or branding of any app, product or business. It comprises many ways like App Store Optimization to in-app messaging, pop-up notifications, messages, emails etc.
In App Store Optimization we optimize apps keywords, contents, images, etc so that whenever a user searches through a related keyword, an app can come in the search. In-app messaging is used to provide information about the new offers and schemes, etc. to the users. Sometimes it is also used for promoting other businesses, apps, etc. Similarly pop-up, notifications, messages, email, etc. play an important role in Mobile App Marketing.