Code mixing refers to alternating between two languages in a single discourse or sentence. It involves transferring linguistic units like words or phrases from one language to another. Code mixing is a natural phenomenon for bilingual individuals and the choice of language is determined by factors like the status of participants and the speech setting. In code mixing between Tamil and English, Tamil typically serves as the matrix language while English words are embedded. Code mixing serves purposes like filling linguistic gaps, social functions, and conversation needs. Exposure to English and its frequent use in different domains influences code mixing in Tamil speech.