A Flurry developer uses Flurry, a mobile analytics tool, to track user interactions within mobile applications. They utilize Flurry's SDKs (Software Development Kits) to integrate the analytics tool into mobile apps. This allows them to monitor user behavior, track in-app events, analyze user demographics, and measure user engagement and retention. They also use Flurry for troubleshooting, as it provides error and crash reporting. Furthermore, they can leverage Flurry's marketing tools to run targeted ad campaigns. Their work is critical for improving app functionality, enhancing user experience, and driving business growth.