In-app purchases allow developers to use the payment systems of app stores like Google Play and the App Store to sell virtual goods from within their apps. This is convenient for users, who can make purchases with one click, but app stores take a 30% commission and prohibit sales through other means. Setting up in-app purchases involves creating product listings with details like names, descriptions, and prices in the app stores' developer interfaces. The code to integrate purchases is relatively simple, with callbacks to handle purchase events, but managing the product listings can be cumbersome. In-app purchases are also required if apps attempt to sell any digital content or features.