Medieval communes in the European Middle Ages had sworn allegiances of mutual defense (both physical defense and of traditional freedoms) among the citizens of a town or city. They took many forms, and varied widely in organization and makeup. Communes are first recorded in the late 11th and early 12th centuries, thereafter becoming a widespread phenomenon. They had the greater development in central-northern Italy, where they were real city-states based on partial democracy, while in Germany they became free cities, independent from local nobility.
The English and French word "commune" appears in Latin records in various forms. They come from Medieval Latin communia, plural form of commune (that which is common, community, state), substantive noun from communis (common). Ultimately, the Proto-Indo-European root is *mey- (to change, exchange).
When independence of rule was won through violent uprising and overthrow, the commune was often called conspiratio (a conspiracy).
During the 10th century in several parts of Western Europe, peasants began to gravitate towards walled population centers, as advances in agriculture (the three-field system) resulted in greater productivity and intense competition. In central and northern Italy, and in Provence and Septimania, most of the old Roman cities had survived—even if grass grew in their streets—largely as administrative centers for a diocese or for the local representative of a distant kingly or imperial power. In the Low Countries, some new towns were founded upon long-distance trade, where the staple was the woolen cloth-making industry. The sites for these ab ovo towns, more often than not, were the fortified burghs of counts, bishops or territorial abbots. Such towns were also founded in the Rhineland. Other towns were simply market villages, local centers of exchange.