Aceh, officially the Province of Aceh, is the westernmost province of Indonesia. It is located on the northern end of Sumatra island, with Banda Aceh being its capital and largest city. It is bordered by the Indian Ocean to the west, Strait of Malacca to the northeast, as well bordering the province of North Sumatra to the east, and shares maritime borders with Malaysia and Thailand to the east, and Andaman and Nicobar Islands of India to the north. Granted a special autonomous status, Aceh is a religiously conservative territory and the only Indonesian province practicing Sharia law officially. There are ten indigenous ethnic groups in this region, the largest being the Acehnese people, accounting for approximately 70% of the region's population of about 5.5 million people in mid-2023. Its area is comparable to Croatia or Togo.

Acehnese or Achinese is an Austronesian language natively spoken by the Acehnese people in Aceh, Sumatra, Indonesia. This language is also spoken by Acehnese descendants in some parts of Malaysia like Yan, in Kedah. Acehnese is used as the co-official language in the province of Aceh, Indonesia. Besides Indonesian used as the official language.