Java (Indonesian: Jawa; Javanese) is an island of Indonesia. With a population of 150 million, Java is home to 51 percent of the Indonesian population, and is the most populous island on Earth. The Indonesian capital city, Jakarta, is located on western Java. Much of Indonesian history took place on Java. It was the center of powerful Hindu-Buddhist empires, the Islamic sultanates, and the core of the colonial Dutch East Indies. Java was also the center of the Indonesian struggle for independence during the 1930s and 1940s. Java dominates Indonesia politically, economically and culturally.

Formed mostly as the result of volcanic eruptions, Java is the 13th largest island in the world and the fifth largest in Indonesia. A chain of volcanic mountains forms an east–west spine along the island. Three main languages are spoken on the island, with Javanese being the dominant; it is the native language of about 60 million people in Indonesia, most of whom live on Java. Most residents are bilingual, with Indonesian as their first or second language. While the majority of the people of Java are Muslim, Java has a diverse mixture of religious beliefs, ethnicities, and cultures.

Java is divided into four provinces, West Java, Central Java, East Java, and Banten, and also two special regions, Jakarta and Yogyakarta.