This article provides an overview of scientific and theoretical works devoted to the study of the features of idioms and idiomatic expressions in Russian linguistics. It is noted that the units in question are an integral part of the language and have important scientific and methodological significance in terms of mastering language skills. An own classification of idiomatic expressions is given according to the function they perform in a communicative situation. It is indicated that there are a number of unstudied aspects in Russian linguistics, which proves the promising orientation of conducting more large-scale studies of their functioning in the language.