Batak is a collective term used to identify a number of closely related Austronesian ethnic groups predominantly found in North Sumatra, Indonesia, who speak Batak languages. The term is used to include the Karo, Pakpak, Simalungun, Toba, Angkola, and Mandailing, related ethnic groups with distinct languages and traditional customs (adat).

The Austronesian languages are a language family widely spoken throughout Maritime Southeast Asia, parts of Mainland Southeast Asia, Madagascar, the islands of the Pacific Ocean and Taiwan. They are spoken by about 386 million people. This makes it the fifth-largest language family by number of speakers. Major Austronesian languages include Malay, Javanese, Sundanese, Tagalog, Malagasy and Cebuano. According to some estimates, the family contains 1,257 languages, which is the second most of any language family.