In the context of businesses and their customers, churn refers to the number of customers that don't renew their subscription or stop buying from a certain brand. Churn can be considered a cost of doing business, with lower churn rates indicating more recurring revenue and a healthier bottom line. The churn rate is calculated as the percentage of total customers that dropped off in a given time period, such as annually, quarterly, or monthly, and is typically reviewed alongside customer acquisition rates to understand the customer journey. Customer churn can be classified into two main categories: voluntary, where a customer chooses to end their contract, and involuntary, where a customer drops off through no direct action on their part. Monitoring churn rates provides insights into the effectiveness of marketing and customer retention efforts, helps identify what influences customer behavior, positions businesses to reduce churn, lowers costs by retaining existing customers over acquiring new ones, and is crucial for companies operating under subscription models.