The Republic of Indonesia, is a transcontinental country in Southeast Asia and Oceania. Comprising 17,508 islands, it is the world's largest archipelagic state. With an estimated population of around 237 million people, it is the world's fourth most populous country and the most populous Muslim-majority nation; however, no reference is made to Islam in the Indonesian constitution. Indonesia is a republic, with an elected legislature and president. The nation's capital city is Jakarta. The country shares land borders with Papua New Guinea, East Timor and Malaysia. Other neighboring countries include Singapore, the Philippines, Australia, and the Indian territory of the Andaman and Nicobar Islands. The Indonesian archipelago has been an important trade region since at least the seventh century, when the Srivijaya Kingdom traded with China and India. Local rulers gradually adopted Indian cultural, religious and political models from the early centuries CE, and Hindu and Buddhist kingdoms flourished. Indonesian history has been influenced by foreign powers drawn to its natural resources. Muslim traders brought Islam, and European powers fought one another to monopolize trade in the Spice Islands of Maluku during the Age of Discovery. Following three and a half centuries of Dutch colonialism, Indonesia secured its independence after World War II.

Across its many islands, Indonesia consists of distinct ethnic, linguistic, and religious groups. The Javanese are the largest and most politically dominant ethnic group. As a unitary state and a nation, Indonesia has developed a shared identity defined by a national language, ethnic diversity, religious pluralism within a majority Muslim population, and a history of colonialism and rebellion against it. Indonesia's national motto, "Bhinneka tunggal ika" ("Unity in Diversity" literally, "many, yet one"), articulates the diversity that shapes the country. However, sectarian tensions and separatism have led to violent confrontations that have undermined political and economic stability. Despite its large population and densely populated regions, Indonesia has vast areas of wilderness that support the world's second highest level of biodiversity. The country is richly endowed with natural resources, yet poverty is a defining feature of contemporary Indonesia.

The name Indonesia derives from the Latin Indus, meaning "India", and the Greek nesos, meaning "island". The name dates to the 18th century, far predating the formation of independent Indonesia. In 1850, George Earl, an English ethnologist, proposed the terms Indunesians and, his preference, Malayunesians for the inhabitants of the "Indian Archipelago or Malayan Archipelago". In the same publication, a student of Earl's, James Richardson Logan, used Indonesia as a synonym for Indian Archipelago. However, Dutch academics writing in East Indies publications were reluctant to use Indonesia. Instead, they used the terms Malay Archipelago (Maleische Archipel); the Netherlands East Indies (Nederlandsch Oost Indië), popularly Indië; the East (de Oost); and even Insulinde.

From 1900, the name Indonesia became more common in academic circles outside the Netherlands, and Indonesian nationalist groups adopted it for political expression. Adolf Bastian, of the University of Berlin, popularized the name through his book Indonesien oder die Inseln des Malayischen Archipels, 1884-1894. The first Indonesian scholar to use the name was Suwardi Suryaningrat (Ki Hajar Dewantara), when he established a press bureau in the Netherlands with the name Indonesisch Pers-bureau in 1913.