Comparative linguistics is devoted to the comparison of languages, normally not of entire languages, but of specific aspects or subsystems of them.
There are two varieties of comparative linguistics, defined by their research interest:
- General-comparative linguistics is a branch of general linguistics which compares languages with the aim of finding traits shared by all languages and, thus, characterizing the human language, and of systematizing the differences among them in order to account for their diversity.
- Historical-comparative linguistics1 is a branch of diachronic linguistics which compares languages with the aim of finding out whether they are cognate, and if so, in which way, in order to set up language families and reconstruct their proto-languages.
2 This traditional name of the discipline is, in most cases, a misnomer, since it mostly deals with prehistorical and reconstructed stages of the languages compared, which are by definition not historical. A more appropriate designation would be ‘diachronic-comparative linguistics’ or ‘genealogical linguistics’.