Recently, code switching has become the key direction in contact linguistics, that is, the transition from one language to another in the course of speech or in literary and journalist texts. The authors' understanding of the theoretical part of the process is based on the analysis of multiple examples representing every aspect of the language theory mentioned in the present study which combines all the approaches to systematic analysis of the phenomenon and aims to find the most suitable by comparing various linguistic theories. Moreover, the present study looks into code copying, a phenomenon adjacent to code switching. The two phenomena are closely related, yet code-copying of differs from code-switching because the latter involves two languages and replaces elements of one code are by elements of another. Code-copying can be considered a part of code-switching and is often a source for the formation of foreign inclusions. As a rule, only a bilingual person who has mastered languages in an organic connection with the culture of corresponding peoples is able to adequately perceive speech in different languages. Searching for the necessary word, several variants of verbalization are activated at once (including variants from alternative lexicons), and the speaker makes a choice in favor of the most suitable variant, while all possible alternatives are suppressed.