This document discusses language choice and multilingualism. It begins by explaining that in multilingual communities, speakers may choose what language to use depending on factors like who they are speaking to, the setting, topic, and goal of the conversation. It then defines diglossia as a situation where two distinct codes are used for different contexts. It also notes that individuals can be bilingual but societies exhibit diglossia. Finally, it defines multilingualism as the ability to communicate fluently in three or more languages, and describes types of multilingualism like official and de facto multilingualism.