What defines "churn" in customer metrics?

Churn is specifically defined as the rate of customer turnover, which refers to the percentage of customers who stop using a product or service over a given time period. This metric is crucial for businesses as it indicates customer retention levels and can impact revenue and growth. A high churn rate suggests that customers are leaving at a faster rate than the company can acquire new ones, which can pose significant challenges for sustainability.

Understanding the churn rate allows startups and businesses to identify problems that might be causing customers to leave and helps inform strategies for improving customer satisfaction and loyalty. Thus, the correct answer effectively captures the essence of what churn entails in customer metrics.

The other options deviate from this definition; for example, the rate of new customer acquisition pertains to how effectively a company is bringing in new customers, while an increase in customer engagement relates to how actively existing customers interact with the product, both of which do not directly concern customer turnover. Lastly, overall profitability of the product focuses on financial performance rather than customer retention dynamics.