Churn rate measures the proportion of customers who cancel, lapse, or disengage within a defined timeframe, typically expressed as a monthly or annual percentage. High churn rate signals that a product, service, or customer experience is failing to deliver sustained value, and it directly erodes revenue growth even when acquisition numbers look healthy. For insights and CMI teams, churn rate is not just a finance metric: it is a diagnostic signal that points toward unmet needs, broken journeys, or positioning gaps that quantitative data alone rarely explains. Understanding why customers churn, not just how many, is where qualitative research becomes essential to any meaningful retention strategy.