Abstract
This review article provides a comprehensive analysis of scholarly works devoted to the phenomenon of vowel harmony (syngarmonism) in Turkic languages. Drawing on research by Turkologists and linguists, the study systematizes the functions of syngarmonism at the phonetic, phonological, morphological, and prosodic levels. It also examines the historical development of the phenomenon, its manifestations in contemporary Turkic dialects, and the factors contributing to the disruption of harmony rules in relation to the internal evolutionary processes of language development. Based on materials from Kazakh, Crimean Tatar, Azerbaijani, and Uzbek, the review analyzes the degree of preservation of labial and palatal harmony, positional alternations of vowels, and assimilation processes, while comparing their articulatory and acoustic characteristics. The study highlights the role of syngarmonism in the formation of grammatical categories and in maintaining the structural integrity of Turkic languages, emphasizing its significance as one of the fundamental indicators of their genetic unity.