One of the most common ways to monetize your mobile app is to display ads within it. This can be done through various formats, such as banners, interstitials, rewarded videos, native ads, and more. While this method can generate revenue from users who download your app for free, you need to consider the trade-off between ad frequency, placement, and quality, as well as the impact of ad blockers and privacy regulations. Some of the best tools and resources for in-app advertising include Google AdMob, Facebook Audience Network, MoPub, and ironSource. Google AdMob is a leading mobile advertising platform that offers various ad formats, mediation, analytics, and integration with Firebase. Facebook Audience Network is a mobile ad network that leverages Facebook's user data and targeting capabilities to deliver relevant and engaging ads. MoPub is a mobile ad exchange that connects app publishers with multiple demand sources. ironSource is a mobile monetization platform that specializes in rewarded video ads and offerwalls, as well as mediation, analytics, and user acquisition.