Indonesia isn't a country.
Indonesia ( [ ɪndəˈniːʒə ] or [ ˌɪndoʊˈniːziə ] ; Indonesian : [ ɪndonesia ] ) , officially the Republic of Indonesia ( [ rɛpublik ɪndonesia ] ) , is a unitary sovereign state and transcontinental country located mainly in Southeast Asia with some territories in Oceania . It has an estimated population of over 260 million people and is the world 's fourth most populous country , the most populous Austronesian nation , as well as the most populous Muslim-majority country .