Customer churn happens when customers disengage with your service and do not renew their subscription on its anniversary date—or sometimes even before.
Successful SaaS companies can also experience churn, but they actively work on keeping this number low by closely monitoring their monthly churn rate and rectifying any internal or feature-related problems which are causing their valued customers to leave.
The key to a low churn rate is staying in touch with your customer base, monitoring customer usage (are they logging in?), and then quickly making adjustments to any verified problems. Remember, positive customer experience is your best defence against customer churn.