Code-switching
The switch is commonly made according to the subject of discourse, but may be for a variety of other reasons such as the mood of the speaker (for example, a person might swear only in French).
Code-switching often occurs in bilingual communities or families. For example, a family that has recently immigrated to a country where a different language is spoken may switch back and forth between that language and their mother tongue, while they are learning the new language. Also, in communities as, for example, the United States with a large number of Spanish speakers, a sentence might have a mixture of Spanish and English words known as "Spanglish" (a similar situation can occur in communities in Canada with both Francophone and Anglophone populations).
In countries such as India, where English is a lingua franca, educated people whose first language is a language other than English but who are also somewhat fluent in English often employ code-switching by inserting English words, phrases or sentences into their conversations. Examples of this type of code-switching can be seen in many Bollywood films.
Code-switching also occurs within a particular language. For instance, a person would likely not use the same words or phrases when speaking to a superior (e.g. an elder, teacher, advisor or supervisor) as they would use when speaking to their friends in an informal atmosphere. Another example is African American Vernacular English among African-Americans.
Code switching is distinct from pidgin, in which features of two languages are combined.
