Multilingualism is the ability to speak more than one language. The ability to speak two languages is "bilingualism," a type of multilingualism. Many immigrants are bilingual and speak languages of both their old and their new country. Multilingualism is useful in many kinds of work, partly because international trade is more common than in past centuries. Some countries and organizations having more than one official language hire people who speak more than one, so they can work with more people. 