The Balto-Slavic languages form a branch of the Indo-European family of languages, traditionally comprising the Baltic and Slavic languages. Baltic and Slavic languages share several linguistic traits not found in any other Indo-European branch, which points to a period of common development. Although the notion of a Balto-Slavic unity has been contested (partly due to political controversies), there is now a general consensus among specialists in Indo-European linguistics to classify Baltic and Slavic languages into a single branch, with only some details of the nature of their relationship remaining in dispute.