In the context of marketing, Retention rate metrics are applied to index and monitor companies’ recent abilities to acquire and keep their own customers. This term is appropriate in contractual situations in which clients/ patients/ employees/ etc. decide to stay on while the period stated in the agreements runs up. In situations that are not under contract, like in purchases, catalogue sales, etc., the term “Current customers” is more appropriate instead. Retention rate is the ratio between the number of customers that choose to go on their contractual terms with a company and those whose obligations expire in the overall perspective. It could also be referred to as “Plowback ratio”.