Indonesian (Bahasa Indonesia) is the official and national language of Indonesia. It is a standardized variety of Malay, an Austronesian language that has been used as a lingua franca in the multilingual Indonesian archipelago for centuries. With over 280 million inhabitants, Indonesia ranks as the fourth-most populous nation globally. According to the 2020 census, over 97% of Indonesians are fluent in Indonesian, making it the largest language by number of speakers in Southeast Asia and one of the most widely spoken languages in the world. Indonesian vocabulary has been influenced by various native regional languages such as Javanese, Sundanese, Minangkabau, Balinese, Banjarese, and Buginese, as well as by foreign languages such as Arabic, Dutch, Hokkien, Portuguese, Sanskrit, and English. Many borrowed words have been adapted to fit the phonetic and grammatical rules of Indonesian, enriching the language and reflecting Indonesia's diverse linguistic heritage.
Most Indonesians, aside from speaking the national language, are fluent in at least one of the more than 700 indigenous local languages; examples include Javanese and Sundanese, which are commonly used at home and within the local community. However, most formal education and nearly all national mass media, governance, administration, and judiciary and other forms of communication are conducted in Indonesian.