For mobile game developers, in-app purchases & ad revenue are the two main sources of income. Through in-app purchases, users can spend real money to purchase in-game virtual goods or currency, such as character cosmetirummy livec upgrades, power-ups, and additional lives. The way that ads are made money in games is by showing banner ads, interstitial ads, or rewarded video ads that give viewers in-game rewards. Developers prefer in-app purchases because they enable a free-to-play business model while collecting money from a portion of the player base. Developers can encourage players to spend money on the game by providing them with appealing virtual goods.