churning

Churning is the act of agitating or stirring a substance within a container known as a churn. The term originated from dairy processing but has since acquired specialized meanings in business, finance, and industry. In everyday usage it can describe rapid, repetitive movement or turnover in a system.

Churning in dairy processing refers to the mechanical agitation of cream until the fat clumps together to form butter and buttermilk. Traditional methods use a wooden barrel and hand crank; modern facilities employ electric churns that control speed and temperature. The process disrupts the fat–water emulsion, allowing butterfat to coalesce and separate from the liquid.

Customer churn, or attrition, is the rate at which customers stop using a product or service over a given period. It is a key metric in subscription businesses. Churn rate is often calculated as the number of customers lost during the period divided by the number at the period's start. Analysts distinguish voluntary from involuntary churn and may track gross churn, net churn, or revenue churn.

In finance, churning describes an abusive practice in which a broker makes excessive trades in a client's account to generate commissions rather than to benefit the client. Signs include high turnover relative to account size, trades lacking justification, or tiny incremental trades. Churning is regulated in many jurisdictions and can lead to disciplinary action, restitution, or penalties.