This chapter is devoted to the concepts and issues that are most important when dealing with multilingualism across societies. It dwells on borrowings and Sprachbund as manifestations of language contact and the three social forms of language use: domains, speech communities and diglossia.

Language contact

People speaking various languages come into contact in a range of situations. The groups of German, French, Romansh and Italian speakers in Switzerland have been neighbours for hundreds of years, and that is how these languages are in contact. For the pupils of a rural primary school in Brunei, language contact occurs when the native speakers of their ethnic languages – Dusun, Penan and Iban – learn English using English and Bahasa Melayu, the official language of the country (Martin 2003). There are countless occasions where language contact occurs: a movement of one group to another group's territory, settling in new countries where other languages are in use, a peaceful takeover of a territory, military conflicts and conquests of one tribe or nation by another, active trade and regular business encounters, missionary activities, intermarriages, and even conversations between individuals – all these are typical situations of language contact.

In the not so distant past, language contact occurred primarily in face-to-face interactions among individuals and groups of speakers. More distant contact took place through written forms, such as documents and books in Latin and Greek. The holy books of the major world religions provide encounters with languages which are not in daily oral use. The Qur’an is written in Classical Arabic, to be read/heeded by the adherents of Islam, who routinely speak different varieties of Arabic (Egyptian Arabic, Moroccan Arabic, Tunisian Arabic) and other languages, including Farsi, Kurdish, Urdu, Malaysian, Tatar, Pashtu or Bosnian, as mother tongues. The sacred texts of Judaism are written in Biblical Hebrew and Talmudic Aramaic, which need interpretation for speakers of modern Hebrew and other languages of believers. The Bible of the Roman Catholic Church was written in Latin before the tradition was partially discontinued in the twentieth century.

New technologies, such as social media, available gadgets and internet with participatory user-generated content, Web 2.0 and incoming third-generation web, made contact between languages, through its speakers, writers, hearers and readers a default situation.