Code is a term that is used instead of 'language, speech, variety, or dialect. Code mixing and code-switching are the phenomena of using two languages simultaneously. These are practiced by those who are proficient bilinguals and during an informal speech.Code-switching refers to the practice of alternating between two languages, that is, uttering some sentences in one language and then switching over to another.It is not considered aberrations because they are used by those who have a working knowledge of the two languages they mix, mother tongue interference falls in the area of errors.This phenomenon occurs when the users superimpose the mother tongue onto the second language. This is often visible in the speech or writing of reasonably proficient users of the second language when they resort to the literal translation of mother-tongue expressions.From the above points, we can make an inference that while moving from formal to informal modes of speech in the same spoken idea, the bilingual speaker engages in Code-switching. Additional Information 'Code-mixing' is the phenomenon of mixing two codes or two languages while speaking. For example, 'Let her be angry, I can't keep ?????? her '.Sociolinguistics is the study of the relationship between language and society. It refers to the way language is used in society. It is concerned with how language use interacts with or is affected by, social factors such as gender, ethnicity, age, or social class.