thumb|260px|The [[Youth Pledge, a pledge made by Indonesian youth on October 28, 1928, defining the identity of the Indonesian nation. On the last pledge, there was an affirmation of Indonesian language as a unifying language throughout the archipelago.]]

thumb|Indonesian language speaker

Indonesian () 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.

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.

Under Indonesian rule from 1976 to 1999, Indonesian was designated as the official language of East Timor. It has the status of a working language under the country's constitution along with English. In November 2023, the Indonesian language was recognized as one of the official languages of the UNESCO General Conference.

The term Indonesian is primarily associated with the national standard dialect (). Standard Indonesian is confined mostly to formal situations, existing in a diglossic relationship with vernacular Malay varieties, which are commonly used for daily communication, coexisting with the aforementioned regional languages and with Malay creoles; which despite its common name is not based on the vernacular Malay dialects of the Riau Islands, but rather represents a form of Classical Malay as used in the 19th and early 20th centuries in the Riau-Lingga Sultanate. Classical Malay had emerged as a literary language in the royal courts along both shores of the Strait of Malacca, including the Johor Sultanate and Malacca Sultanate. Originally spoken in Northeast Sumatra, Malay has been used as a lingua franca in the Indonesian archipelago for half a millennium. It might be attributed to its ancestor, the Old Malay language (which can be traced back to the 7th century). The Kedukan Bukit inscription is the oldest surviving specimen of Old Malay, the language used by Srivijayan empire.

Indonesian (in its standard form) has essentially the same material basis as the Malaysian standard of Malay and is therefore considered to be a variety of the pluricentric Malay language. However, it does differ from Malaysian Malay in several respects, with differences in pronunciation and vocabulary, especially within technical and administrative contexts. These differences are due mainly to the Dutch and Javanese influences on Indonesian. Indonesian was also influenced by the (), which was the lingua franca of the archipelago in colonial times, and thus indirectly by other spoken languages of the islands.

Malaysian Malay claims to be closer to the classical Malay of earlier centuries, even though modern Malaysian has been heavily influenced, in lexicon as well as in syntax, by English. The question of whether High Malay (Court Malay) or Low Malay (Bazaar Malay) was the true parent of the Indonesian language is still debated. High Malay was the official language used in the court of the Johor Sultanate and continued by the Dutch-administered territory of Riau-Lingga, while Low Malay was commonly used in marketplaces and ports of the archipelago. Some linguists have argued that it was the more common Low Malay that formed the base of the Indonesian language.

Old Malay as lingua franca

thumb|For centuries, [[Srivijaya, through its expansion, economic power and military prowess, was responsible for the wide spread of Old Malay throughout the Malay Archipelago. It was the working language of traders and it was used in various ports and marketplaces in the region.|224x224px]]

Trade contacts carried on by various ethnic peoples at the time were the main vehicle for spreading the Old Malay language, which was the main communications medium among the traders. Ultimately, the Old Malay language became a lingua franca and was spoken widely by most people in the archipelago. The beginning of the common era saw the growing influence of Indian civilisation in the archipelago. With the penetration and proliferation of Sanskrit vocabulary and the influence of major Indian religions such as Hinduism and Buddhism, Ancient Malay evolved into the Old Malay. The oldest uncontroversial specimens of Old Malay are the 7th century CE Sojomerto inscription from Central Java, Kedukan Bukit inscription from South Sumatra, Indonesia and several other inscriptions dating from the 7th to 10th centuries discovered in Sumatra, Java, other islands of the Sunda archipelago, as well as Luzon, Philippines. All these Old Malay inscriptions used either scripts of Indian origin such as Pallava, Nagari or the Indian-influenced old Sumatran characters. The Old Malay system is greatly influenced by Sanskrit scriptures in terms of phonemes, morphemes, vocabulary and the characteristics of scholarship, particularly when the words are closely related to Indian culture. Further research stated that Old Malay and Modern Malay are forms of the same language, in spite of some considerable differences between them.

Classical Malay of Riau-Lingga

Standard Indonesian is a standard language of "Riau Malay",

Dutch East Indies Colonial Malay

When the Dutch East India Company (VOC) first arrived in the archipelago at the start of the 1600s, the Malay language was a significant trading and political language due to the influence of the Malaccan Sultanate and later the Portuguese. However, the language had never been dominant among the population of the Indonesian archipelago as it was limited to mercantile activity. The VOC adopted the Malay language as the administrative language of their trading outpost in the east. Following the bankruptcy of the VOC, the Batavian Republic took control of the colony in 1799, and it was only then that education in and promotion of Dutch began in the colony. In 1864, the Dutch colonial government therefore decided to disseminate this language - and not Dutch - throughout the colony. To this end, the colonial government stimulated the study, standardisation and modernisation of Malay, imposing it via its institutions, via education, the missions and the media, and via the literary works produced by the state publishers Balai Poestaka. In this respect, the Dutch pursued a non-chauvinistic cultural policy. In reality, Klinkert's pure Malacca or Riau Malay was unusable in the eastern part of Indies even in the coastal regions.

The birth of Indonesian: adoption as the national language

The nationalist movement that ultimately brought Indonesian to its national language status rejected Dutch from the outset. However, the rapid disappearance of Dutch was a very unusual case compared with other colonized countries, where the colonial language generally has continued to function as the language of politics, bureaucracy, education, technology, and other fields of importance for a significant time after independence. The ease with which Indonesia eliminated the language of its former colonial power can perhaps be explained as much by Dutch policy as by Indonesian nationalism. In marked contrast to the French, Spanish and Portuguese, who pursued an assimilation colonial policy, or even the British, the Dutch did not attempt to spread their language among the indigenous population. In fact, they consciously prevented the language from being spread by refusing to provide education, especially in Dutch, to the native Indonesians so they would not come to see themselves as equals. By the time they tried to counter the spread of Malay by teaching Dutch to the natives, it was too late, and in 1942, the Japanese conquered Indonesia. The Japanese mandated that all official business be conducted in Indonesian and quickly outlawed the use of the Dutch language. Three years later, the Indonesians themselves formally abolished the language and established bahasa Indonesia as the national language of the new nation. and Tabrani had further proposed the term over calling the language Malay language during the First Youth Congress in 1926.

thumb|The [[Youth Pledge was the result of the Second Youth Congress held in Batavia in October 1928. On the last pledge, there was an affirmation of Indonesian language as a unifying language throughout the archipelago.]]

Several years prior to the congress, Swiss linguist, Renward Brandstetter wrote An Introduction to Indonesian Linguistics in 4 essays from 1910 to 1915. The essays were translated into English in 1916. By "Indonesia", he meant the name of the geographical region, and by "Indonesian languages" he meant Malayo-Polynesian languages west of New Guinea, because by that time there was still no notion of Indonesian language.

Sutan Takdir Alisjahbana was a great promoter of the use and development of Indonesian and he was greatly exaggerating the decline of Dutch. Higher education was still in Dutch and many educated Indonesians were writing and speaking in Dutch in many situations (and were still doing so well after independence was achieved). He believed passionately in the need to develop Indonesian so that it could take its place as a fully adequate national language, able to replace Dutch as a means of entry into modern international culture. In 1933, he began the magazine Pujangga Baru (New Writer — Poedjangga Baroe in the original spelling) with co-editors Amir Hamzah and Armijn Pane. The language of Pujangga Baru came in for criticism from those associated with the more classical School Malay and it was accused of publishing Dutch written with an Indonesian vocabulary. Alisjahbana would no doubt have taken the criticism as a demonstration of his success. To him the language of Pujangga Baru pointed the way to the future, to an elaborated, Westernised language able to express all the concepts of the modern world. As an example, among the many innovations they condemned was use of the word bisa instead of dapat for 'can'. In Malay bisa meant only 'poison from an animal's bite' and the increasing use of Javanese bisa in the new meaning they regarded as one of the many threats to the language's purity. Unlike more traditional intellectuals, he did not look to Classical Malay and the past. For him, Indonesian was a new concept; a new beginning was needed and he looked to Western civilisation, with its dynamic society of individuals freed from traditional fetters, as his inspiration.

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Indonesian language in Japanese occupation, Old Order, and New Order

Once the Japanese overturned Dutch rule, a prohibition on the use of the Dutch language led to an expansion of Indonesian language newspapers and pressure on them to increase the language's wordstock. The Japanese agreed to the establishment of the Komisi Bahasa (Language Commission) in October 1942, formally headed by three Japanese but with a number of prominent Indonesian intellectuals playing the major part in its activities. Soewandi, later to be Minister of Education and Culture, was appointed secretary, Alisjahbana was appointed an 'expert secretary' and other members included the future president and vice-president, Sukarno and Hatta. Journalists, beginning a practice that has continued to the present, did not wait for the Komisi Bahasa to provide new words, but actively participated themselves in coining terms. Many of the Komisi Bahasa's terms never found public acceptance and after the Japanese period were replaced by the original Dutch forms, including jantera (Sanskrit for 'wheel'), which temporarily replaced mesin (machine), ketua negara (literally 'chairman of state'), which had replaced presiden (president) and kilang (meaning 'mill'), which had replaced pabrik (factory). In a few cases, however, coinings permanently replaced earlier Dutch terms, including pajak (earlier meaning 'monopoly') instead of belasting (tax) and senam (meaning 'exercise') instead of gimnastik (gymnastics). The Komisi Bahasa is said to have coined more than 7000 terms, although few of these gained common acceptance. The combination of nationalistic, political, and practical concerns ultimately led to the successful adoption of Indonesian as a national language. In 1945, Javanese was easily the most prominent language in Indonesia. It was the native language of nearly half the population, the primary language of politics and economics, and the language of courtly, religious, and literary tradition. What it lacked, however, was the ability to unite the diverse Indonesian population as a whole. With thousands of islands and hundreds of different languages, the newly independent country of Indonesia had to find a national language that could realistically be spoken by the majority of the population and that would not divide the nation by favouring one ethnic group, namely the Javanese, over the others. In 1945, Indonesian was already in widespread use; Today, Indonesian continues to function as the language of national identity as the Congress of Indonesian Youth envisioned, and also serves as the language of education, literacy, modernization, and social mobility.

Standard Indonesian is used in books and newspapers and on television/radio news broadcasts. The standard dialect, however, is rarely used in daily conversations, being confined mostly to formal settings. While this is a phenomenon common to most languages in the world (for example, spoken English does not always correspond to its written standards), the proximity of spoken Indonesian (in terms of grammar and vocabulary) to its normative form is noticeably low. This is mostly due to Indonesians combining aspects of their own local languages (e.g., Javanese, Sundanese, and Balinese) with Indonesian. This results in various vernacular varieties of Indonesian, the very types that a foreigner is most likely to hear upon arriving in any Indonesian city or town. This phenomenon is amplified by the use of Indonesian slang, particularly in the cities. Unlike the relatively uniform standard variety, Vernacular Indonesian exhibits a high degree of geographical variation, though Colloquial Jakartan Indonesian functions as the de facto norm of informal language and is a major source of influence throughout the archipelago.

The most common and widely used colloquial Indonesian is heavily influenced by the Betawi language, a Malay-based creole of Jakarta, amplified by its popularity in Indonesian popular culture in mass media and Jakarta's status as the national capital. In informal spoken Indonesian, various words are replaced with those of a less formal nature. For example, (no) is often replaced with the Betawi form or the even simpler , while (like, similar to) is often replaced with . or (very), the term to express intensity, is often replaced with the Javanese-influenced . As for pronunciation, the diphthongs ai and au on the end of base words are typically pronounced as and . In informal writing, the spelling of words is modified to reflect the actual pronunciation in a way that can be produced with less effort. For example, becomes or , becomes , becomes . In verbs, the prefix me- is often dropped, although an initial nasal consonant is often retained, as when becomes (the base word is ). The suffixes -kan and -i are often replaced by -in. For example, becomes , becomes . The latter grammatical aspect is one often closely related to the Indonesian spoken in Jakarta and its surrounding areas.

Malay historical linguists agree on the likelihood of the Malay homeland being in western Borneo. A form known as Proto-Malay language was spoken in Borneo at least by 1000 BCE and was, it has been argued, the ancestral language of all subsequent Malayan languages. Its ancestor, Proto-Malayo-Polynesian, a descendant of the Proto-Austronesian language, began to break up by at least 2000 BCE, possibly as a result of the southward expansion of Austronesian peoples into Maritime Southeast Asia from the island of Taiwan. Indonesian, which originated from Malay, is a member of the Austronesian family of languages, which includes languages from Southeast Asia, the Pacific Ocean and Madagascar, with a smaller number in continental Asia. The formal register has a high degree of mutual intelligibility with the Malaysian standard of Malay, which is officially known there as , despite the numerous lexical differences. However, vernacular varieties spoken in Indonesia and Malaysia share limited intelligibility, which is evidenced by the fact that Malaysians have difficulties understanding Indonesian sinetron (soap opera) aired on Malaysia TV stations, and vice versa. This gap is further widened by a significant degree of diglossia, as the use of informal registers and slang (Bahasa Gaul) in media, such as soap operas and animated series, differs markedly from the formal standard.

Malagasy, a geographic outlier spoken in Madagascar in the Indian Ocean; the Philippines national language, Filipino; Formosan in Taiwan's aboriginal population; and the native Māori language of New Zealand are also members of this language family. Although each language of the family is mutually unintelligible, their similarities are rather striking. Many roots have come virtually unchanged from their common ancestor, Proto-Austronesian language. There are many cognates found in the languages' words for kinship, health, body parts and common animals. Numbers, especially, show remarkable similarities.

{|class="wikitable sortable" style="text-align:center"

|+ Numbers in Austronesian languages

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! Language

! 1 (one)

! 2 (two)

! 3 (three)

! 4 (four)

! 5 (five)

! 6 (six)

! 7 (seven)

! 8 (eight )

! 9 (nine)

! 10 (ten)

|-

! PAN,

| *isa || *DuSa || *telu || *Sepat || *lima || *enem || *pitu || *walu || *Siwa || *puluq

|-

! Indonesian

| || || || || || || || || ||

|-

! Malay

| || || || || || || || || ||

|-

! Amis

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|-

! Balinese

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|-

! Sundanese

| || || || || || || || || ||

|-

! Tsou

| || || || || || || || || ||

|-

! Tagalog

| || || || || || || || || ||

|-

! Ilocano

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|-

! Cebuano

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|-

! Hiligaynon

| || || || || || || || || ||

|- align=center

! Chamorro

| || || || || || || || || ||

|-

! Malagasy

| || || || || || || || || ||

|-

! Cham

| sa || dua || klau || pak || limâ || nam || tajuh || dalipan || thalipan || pluh

|-

! Toba Batak

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|-

! Minangkabau

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|-

! Rejang

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! Sasak

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! Javanese

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! Tetum

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! Sumbawa

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! Biak

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! Fijian

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! Kiribati

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! Samoan

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! Hawaiian

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|}

There are more than 700 local languages in Indonesian islands, such as Javanese, Sundanese, etc. While Malay as the source of Indonesian is the mother tongue of ethnic Malay who lives along the east coast of Sumatra, in the Riau Archipelago, and on the south and west coast of Kalimantan (Borneo). There are several areas, such as Jakarta, Manado, Lesser Sunda islands, and Mollucas which has Malay-based trade languages. Thus, a large proportion of Indonesians use at least two languages daily, including Indonesian and local languages. When two languages are used by the same people in this way, they are likely to influence each other. Loanwords from Portuguese were mainly connected with articles that the early European traders and explorers brought to Southeast Asia. Indonesian also receives many English words as a result of globalization and modernization, especially since the 1990s, as far as the Internet's emergence and development until the present day. Some Indonesian words correspond to Malay loanwords in English, among them the common words orangutan, gong, bamboo, rattan, sarong, and the less common words such as paddy, sago and kapok, all of which were inherited in Indonesian from Malay but borrowed from Malay in English. The phrase "to run amok" comes from the Malay verb (to run out of control, to rage).

Indonesian is neither a pidgin nor a creole since its characteristics do not meet any of the criteria for either. It is believed that the Indonesian language was one of the means to achieve independence, but it is opened to receive vocabulary from other foreign languages aside from Malay that it has made contact with since the colonialism era, such as Dutch, English and Arabic among others, as new loan words are added every year.

Geographical distribution

According to the 2025 census, Indonesian had 80 million native speakers and 180 million second-language speakers, In Australia, Indonesian is one of three Asian target languages, together with Japanese and Mandarin, taught in some schools as part of the Languages Other Than English programme. Indonesian has been taught in Australian schools and universities since the 1950s.

In East Timor, which was occupied by Indonesia between 1975 and 1999, Indonesian is recognized by the constitution as one of the two working languages (the other being English), alongside the official languages of Tetum and Portuguese. the Netherlands, Japan, South Korea, Timor-Leste, Vietnam, Taiwan, the United States, and the United Kingdom.

Official status

thumb|Indonesian is also the language of Indonesian mass media, such as magazines. Printed and broadcast mass media are encouraged to use standard Indonesian, although more relaxed popular slang often prevails.

Indonesian is the official language of Indonesia, and its use is encouraged throughout the Indonesian archipelago. It is regulated in Chapter XV, 1945 Constitution of Indonesia about the flag, official language, coat of arms, and national anthem of Indonesia.