Mobile app crashes significantly impact user experience, with studies showing that 80% of users will uninstall an app after experiencing three or fewer crashes. The key to understanding app stability is monitoring crash-free sessions, which indicate how often users experience an uninterrupted app experience. While calculating crash-free rates can be straightforward, it is crucial to consider different metrics, such as crash-free users versus crash-free sessions, to get a holistic view of app performance. Industry benchmarks suggest that apps with crash-free session rates below 99.9% are more likely to receive poor app store ratings, while high-performing apps aim for over 99.95% crash-free sessions. However, crash-free rates can be misleading if other stability issues, like Out of Memory (OOM) and Application Not Responding (ANR) errors, are not considered. To improve crash-free rates, continuous testing, effective crash reporting, and structured release management are essential practices. Understanding these metrics and practices helps developers maintain app stability and enhance user experience.