This document discusses language choice in multilingual communities. It defines key concepts such as linguistic repertoire, diglossia, bilingualism, and multilingualism. Linguistic repertoire refers to the set of language skills and knowledge a person has, including varieties like dialects. Diglossia describes a situation where two varieties of the same language are used for different contexts, with one being more prestigious. Bilingualism refers to the ability to use two languages interchangeably. Multilingualism is the ability to communicate in three or more languages. The document also discusses language interference, which refers to applying knowledge from one's native language to a second language.