What is Customer Churn
Customer churn happens when your users stop using your app - either they don't use it for a very long time, or they uninstall the app from their device.
Why does Customer Churn matter
No matter what you do, you cannot completely erase customer churn, so you shouldn't try to. Every brand, every app and every online store will have users leaving for reasons you cannot control. What you should do, is ensure you've taken all the steps to ensure your churn rate is as low as it could possibly be. By analyzing the rate at which your users stop using your app, you can determine what changes need to be made (for example, improving UX/UI, reducing pricing, adding new features or optimizing user flow).
If your app or online store accounts deliver a very high churn rate, it could mean that while your user acquisition and lead generation processes work great, you are not leveraging user experience as much as you should to get the maximum return from every new account. Thus, you should focus on user retention programs - or starting one if you haven't already.