AdMob is a mobile advertising platform created by Google that allows app developers to monetize their applications through ads. It provides a variety of ad formats, including banners, interstitials, and rewarded video ads, enabling developers to choose the best fit for their app's user experience. By integrating AdMob into their apps, developers can earn revenue while providing free content to users. The platform also offers tools for tracking ad performance and optimizing revenue, making it easier for developers to manage their advertising strategies effectively.