Churn rate is a measure of the percentage of customers or users who stop doing business with a company over a given period of time. This metric is commonly used by companies that offer subscription-based products or services, as it provides a way to measure the retention rate of their customer base.

For example, a company that sells software as a service (SaaS) might have 100 customers at the beginning of a month. Over the course of that month, 10 of those customers decide to cancel their subscriptions. In this case, the company's churn rate for that month would be (10 / 100) x 100 = 10%.

This means that 10% of the company's customers churned or cancelled their subscriptions during that month.