Java is an island in Indonesia and is the 13th largest in the world. With a population of nearly 160 million, the island is home to the world’s largest population and is one of the most populous places in the world. Although it only occupies the fifth largest, Java is inhabited by 60% of Indonesia’s population. This figure is decreased when compared to the 1905 population census which reaches 80.6% of the population of Indonesia. The population decline in Java Island by percentage is caused by population movement ( Transmigration) from Java Island to all over Indonesia. The capital of Indonesia, Jakarta, is located in northwestern Java (precisely at the westernmost tip of the Pantura Line).
Most of the people speak in three major languages. Javanese is the mother tongue of 100 million Indonesians, and most of its speakers live on the island of Java. Most of the population is bilingual, who speak Indonesian both as a first and second language. The other two important languages are Sundanese and Betawi. Most of the population of Java Island is Muslim and Christian, but there are various beliefs, religions, ethnic groups, and cultures on the island.
With a population of 160 million, Java is an island that houses more than 60% of the Indonesian population. With a density of 1,317 souls / km², the island is also one of the world’s most populous islands. Approximately 45% of Indonesia’s population comes from Javanese ethnicity. However, the western third of the island (West Java, Banten, and Jakarta) has a population density of over 1,500 inhabitants / km2.
Java has an area of about 126,700 km2.  The longest river is Bengawan Solo, which is 600 km long.  This river is sourced in central Java, precisely in Lawu volcano. The river flow then flows north and east, towards its estuary in the Java Sea near the city of Surabaya.
Almost the entire Javanese region has had the impact of volcanic activity. There are thirty-eight mountains stretching from east to west of the island, all of which have at times been active volcanoes. The highest volcano in Java is Mount Semeru (3,676 m), while the most active volcano in Java and even in Indonesia is Mount Merapi (2,968 m) and Mount Kelud (1731 m). The distant mountains and plateau help the inland areas to be divided into areas that are relatively isolated and suitable for wetland rice fields. Paddy rice fields in Java are among the most fertile in the world.  Java is the first place to plant coffee in Indonesia, which is since 1699. Now, arabica coffee is widely grown in the Highlands of Ijen either by small farmers or by large estates.
The average temperature throughout the year is between 22 ° C to 29 ° C, with an average humidity of 75%. The northern coast is usually hotter, with an average of 34 ° C during the day in the dry season. The south coast is generally cooler than the north coast, and the upland plateau is cooler. The rainy season begins in October and ends in April, where the rain usually falls in the afternoon, and in the months other than that it usually only goes down intermittently. The highest rainfall generally occurs in the months of January and February.