Demographics of Indonesia, Languages of Indonesia, and Religion in Indonesia

The national population from the 2000 national census is 206 million, and the Indonesian Central Statistics Bureau and Statistics Indonesia estimate a population of 222 million for 2006. 130 million people live on the island of Java, the world's most populous island. Despite a fairly effective family planning program that has been in place since the 1960s, the population is expected to grow to around 254 million by 2020 and 288 million by 2050.

An ethnic Minangkabau woman in traditional dress. There are around 300 distinct native ethnicities in Indonesia.

Most Indonesians are descended from Austronesian-speaking peoples whose languages can be traced to Proto Austronesian (PAn), which likely originated on Taiwan. The other major grouping are Melanesians, who inhabit eastern Indonesia. There are around 300 distinct native ethnicities in Indonesia, and 742 different languages and dialects. The largest ethnic group is the Javanese, who comprise 42% of the population, and are politically and culturally dominant. The Sundanese, ethnic Malays, and Madurese are the largest non-Javanese groups. A sense of Indonesian nationhood exists alongside strong regional identities. Society is largely harmonious, although social, religious and ethnic tensions have triggered horrendous violence. Chinese Indonesians are an influential ethnic minority comprising less than 1% of the population. Much of the country's privately owned commerce and wealth is Chinese-controlled, which has contributed to considerable resentment, and even anti-Chinese violence.

The Istiqlal Mosque and Jakarta Cathedral in Central Jakarta. Indonesia has the world's largest population of Muslims

The official national language, Indonesian, is universally taught in schools, and consequently is spoken by nearly every Indonesian. It is the language of business, politics, national media, education, and academia. It was constructed from a lingua franca that was in wide use throughout the region, and is thus closely related to Malay which is an official language in Malaysia, Brunei, and Singapore. Indonesian was first promoted by nationalists in the 1920s, and declared the official language on the proclamation of independence in 1945. Most Indonesians speak at least one of the several hundred local languages (bahasa daerah), often as their first language. Of these, Javanese is the most widely spoken as the language of the largest ethnic group. On the other hand, Papua has over 270 indigenous Papuan and Austronesian languages, in a region of about 2.7 million people. A significant fraction of the people who attended school before independence can speak Dutch to some extent.

Although religious freedom is stipulated in the Indonesian constitution, the government officially recognizes only six religions: Islam, Protestantism, Roman Catholicism, Hinduism, Buddhism, and Confucianism. Although it is not an Islamic state, Indonesia is the world's most populous Muslim-majority nation, with 86.1% of Indonesians declared Muslim according to the 2000 census. 8.7% of the population is Christian, 3% are Hindu, and 1.8% Buddhist or other. Most Indonesian Hindus are Balinese, and most Buddhists in modern-day Indonesia are ethnic Chinese. Though now minority religions, Hinduism and Buddhism remain defining influences in Indonesian culture. Islam was first adopted by Indonesians in northern Sumatra in the 13th century, through the influence of traders, and became the country's dominant religion by the 16th century. Roman Catholicism was brought to Indonesia by early Portuguese colonialists and missionaries, and the Protestant denominations are largely a result of Dutch Calvinist and Lutheran missionary efforts during the country's colonial period. A large proportion of Indonesians—such as the Javanese abangan, Balinese Hindus, and Dayak Christians—practice a less orthodox, syncretic form of their religion, which draws on local customs and beliefs.