There are about 583 languages spoken by as many distinct ethnic groups across the archipelago. There are five main language groups on Sumatra alone, six on Sulawesi and three on Java. One small island, Alor in Nusa Tengggara has seven different language groups. The Balinese speak their own, and many local languages are further divided by special forms for addressing someone of inferior, equal or superior social status. Adding even more spice to this linguistic stew, all these languages are also spoken in a number of different local dialects.

Bahasa Indonesia, the official national language, is akin to Malay, and is written in Roman script and based on European orthography. English is the most widely used foreign language for business and travel alike. Wherever you go you will be greeted by the familiar "Hello Mr.!", (regardless of your sex), and even if your travels take you off the beaten track' it is not uncommon to find Indonesians with a decent command of the English language. In some of the bigger cities and tourist destinations Dutch is still used, and the influence of Dutch in Bahasa Indonesia is quite obvious. French is increasing its popularity at the better hotels and restaurants.