Indonesia (Bahasa Indonesia') is the official national language of Indonesia. It is based on a version of Malay from the Riau islands in western Indonesia. It was first declared the official language with the declaration of Indonesian independence in 1945, following the 1928 unifying-language declaration in the Indonesian Youth Pledge.
Almost 100% of Indonesia's 240 million inhabitants speak the language and it is one of most widely spoken languages in the world. Most Indonesians, aside from speaking the national language, are often fluent in another regional language or local dialect (examples include Minangkabau, Sundanese, Javanese and Balinese) that are commonly used at home and within the local community. Most formal education, as well as nearly all national media and other forms of communication, are conducted in Indonesian. In East Timor, which was annexed as an Indonesian province from 1975 to 1999, the Indonesian language is recognised by the constitution as one of two working languages (the other is English, alongside the official languages of Tetum and Portuguese).
The Indonesian name for the language is Bahasa Indonesia (lit. "the language of Indonesia"). This term can sometimes still be found in written or spoken English. In addition, the language is sometimes referred to as "Bahasa" by English speakers, though this simply means "language" and thus is also not an official term for the Indonesian language.