“Secret languages” and “language of the outcasts”. The conspiracy function of professional jargons in the 17th–20th centuries. Reasons for and the history of their creation; the content of the limited vocabulary of the “secret language”; the origin of the cantisms of the artificial languages; grecisms. Language of the criminal world. The structure of the Russian declassed cant. Principal differences from the language of craftsmen. Linguistic succession of sociolects. The three main periods of the formation of primary sociolects of the Russian national language.