Topic summary
Common language

Extracted from the Wikipedia article Lingua franca.
German
German is used as a lingua franca in Central Europe and historically in Eastern and Northern Europe, and continues to be one to some extent. As German speakers became established in these regions in Early modern Europe, Low German and later the modern standardized form of High German became the prestigious language of the urban centers, eventually becoming the common language of the Hanseatic League and later, lands ruled under the Holy Roman Empire and Habsburg monarchy. Its prominence outside of Europe grew in the 19th century, becoming a common language in science and other academic fields such as psychology, and despite the rise of English, continues to serve as an important lingua franca.