Churn is generally measured in two broad categories: revenue churn, which measures the dollar value of contracts not renewed, and customer churn, which is commonly expressed as the percentage of companies up for renewal that do not extend their contract. Within each of these categories are several more specific views, from the predictable (net vs. gross or churn within company size or industry cohorts) to the nuanced [preventable churn (unhappy customers, inactive users) vs. structural churn (customer went out of business or was acquired)].