The civil law tradition is the oldest and most prevalent legal tradition in the world today, embracing the legal systems of Continental Europe, Latin America and those of many African and Asian countries. Despite notable variations in substantive laws, civil law countries share a fundamental unity. This unity primarily stems from their common historical sources and the classification of their legal institutions according to a universally accepted scheme that predates their independent development, which they later adopted and adapted. The evolution of the civil law tradition was shaped by the interaction of three principal influences: Roman law, as preserved and transmitted through Emperor Justinian’s sixth-century codification; Germanic customary law; and canon law, which, while significantly influenced by Roman law, developed into a distinct legal system. Particularly instrumental in this process were medieval jurists, who systematically studied, interpreted, and adapted Roman law to suit the conditions of their time. From the fifteenth century onward, the relationship between Roman law, Germanic customary law, and canon law was increasingly influenced by the rise of the nation-state and the consolidation of centralized political administrations. This chapter examines the shared history of European civil law from its origins in the Middle Ages to the development of national codifications in the eighteenth and nineteenth centuries. It highlights the key historical factors that facilitated the preservation, revival, and eventual reception of Roman law, which became the foundation of the ius commune—the common legal framework of Continental Europe. Additionally, the chapter explores the global influence of the civil law tradition and outlines its fundamental characteristics.