As of 2017, this question doesn't have a complex answer. German is the sole official language in three countries. They are Germany, Austria, and Liechtenstein. German is a co-official language in three countries: Switzerland, Belgium, and Luxembourg.

It is also used as the co-official language of the European Union (EU), which is a political and economic union of 28 member states that are located primarily in Europe. Additionally, it is interesting to note that several other countries, including Denmark, Hungary, Italy, and Poland, have German as a national minority language.

Viewing its origin, it has been stated by experts that German belongs to the West Germanic group in the Indo-European language family, along with English, Frisian, and Dutch (Netherlandic, Flemish).

More Info: en.wikipedia.org