Flurry is a helpful tool that helps developers and marketers understand how their mobile apps are being used and how effective their marketing campaigns are. It provides lots of useful information and insights, such as how many people have downloaded the app, what they do within the app, and which marketing campaigns are the most effective. Flurry also has tools to help re-engage users who have already downloaded the app and to target specific groups of users with personalized campaigns. It's a useful tool for anyone looking to make the most of their mobile app and marketing efforts.