In-app advertising refers to the practice of displaying ads within mobile apps. In-app advertising allows advertisers to reach users who are actively using mobile apps, and to deliver ads to them in a context that is relevant and engaging. In-app advertising can be effective for both advertisers and app developers, as it can provide advertisers with access to a large and engaged audience, and can provide app developers with an additional source of revenue. In-app advertising is typically delivered through a combination of ad networks, and can be targeted to specific users based on a variety of factors, such as demographics, behavior, or location.