The vocabulary (mainly abstract and literary words), principles of word formations, and, to some extent, inflections and literary style of Russian have been also influenced by Church Slavonic, a developed and partly russified form of the South Slavic Old Church Slavonic language used by the Russian Orthodox Church. However, the East Slavic forms have tended to be used exclusively in the various dialects that are experiencing a rapid decline. In some cases, both the East Slavic and the Church Slavonic forms are in use, with many different meanings. For details, see Russian phonology and History of the Russian language.