Credit relations have not been thoroughly examined by modern historians and are usually viewed through the lens of evolutionist narratives recounting the victory of “ economic rationality” by means of the institutionalization, formalization, and modernization of these relations, although the veritable meaning of these terms are never precisely defined. This article examines the notion of credit relations by exploring their formalization and personalization, which are viewed as two relatively compatible elements. Drawing on a survey of recent publications on the subject, this article analyzes the complementarity of the various types of people involved in credit relations, the transformation of the tools for undertaking such a transaction, and the difficulties surrounding credit in addition to the (non-)existence of sanctions.