Branch of linguistics concerned with examining changes in phonology , grammar , and semantics during a language's evolution, reconstructing earlier stages, and uncovering evidence of the influence of other languages.
Its roots are in Classical and medieval writings on etymology and in the comparative study of Greek and Latin during the Renaissance. Only in the 19th century did more scientific language-analysis methods lead to the development of historical linguistics as a scholarly discipline. The Neogrammarians, a group of German linguists who formulated sound correspondences in the Indo-European language s, were especially influential. In the 20th century the methods of historical linguistics were extended to other language groups.