Language family

A language family is a group of languages related through descent from a common ancestor, called the proto-language of that family. The term 'family' reflects the tree model of language origination in historical linguistics, which makes use of a metaphor comparing languages to people in a biological family tree, or in a subsequent modification, to species in a phylogenetic tree of evolutionary taxonomy. No actual biological relationship between speakers is implied by the metaphor.

Estimates of the number of living languages vary from 5,000 to 8,000, depending on the precision of one's definition of "language", and in particular on how one classifies dialects. The 2013 edition of Ethnologue catalogs just over 7,000 living human languages. A "living language" is simply one that is used as the primary form of communication of a group of people. There are also many dead and extinct languages, as well as some that are still insufficiently studied to be classified, or even unknown outside their respective speech communities.