Although the phraseologisms were appeared, developed and involved in researchs throughout history, phraseology is referred to as a field of lexicology both in general linguistics, in turkology and in the study of modern Azerbaijani. Even in the modern language textbooks the totality of all words, terms and phraseologisms that are included in the vocabulary structure of language is called lexicon. The main research object of lexicology is the word, that is, lexicology is the science about word. The vocabulary structure of the modern Azerbaijani language includes all the words and phrases that play a role in the speech. In linguistics, a totality of all grammatical forms and meanings of the word is called lexem. Lexicology, first of all, studies the extralinguistic and socio-historical factors of vocabulary structure of language. The phraseology, an integral part of lexicology, is about the formation, development and use of phraseological units. The totality of all fixed word combinations in the language is called phraseology. These combinations are formed on the basis of grammatical compounds. To study phraseology as a separate field of linguistics, it is necessary base on the language categories that it possesses. The article describes in detail phraseological units. The components, that make up the phraseological units are integral parts and are closely interconnected. Often these components are in a stable position. The article also examines the main features of phraseological units. There are many features of phraseological units.The objective study of the functional properties of the phraseological units is related to their internal form and semantic integrity. It is impossible to speak about modeling without learning the inner form of phraseology and paying particular attention to it. In turn, structuralsemantic models of the phraseological unit enable the full disclosure of its essence. Some of the phraseological units may be decomposed into free word combinations with the same lexical content. The article also describes in detail the types of the phraseological units. The phraseological units are classified according to their degree of semantic integrity: junction, compatibility and combination.
During the study of phraseological units, the development path of phraseological units is also taken into account.