Indonesian or Bahasa Indonesia, based on the Riau version of Malay language, was declared the official language with the declaration of Indonesia's independence in 1945, following the 1928 "unifying language" declaration in the Indonesian Youth Pledge.
With fluency approaching 100% among the quarter billion inhabitants of the world's fourth most populous nation, Bahasa Indonesia has become one of the 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 and Javanese) which 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 an Indonesian province from 1975 to 1999, the Indonesian language is recognised by the constitution as one of the 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.