Nahdlatul Ulama is an Islamic organization in Indonesia. Its membership estimates range from 40 million (2013) to over 90 million (2019), making it the largest Islamic organization in the world. NU also is a charitable body funding schools and hospitals as well as organizing communities to help alleviate poverty.

The NU was founded in 1926 by a ulema and merchants to defend both traditionalist Islamic practices (in accordance with Shafi’i school) and its members’ economic interests. NU’s religious views are considered “traditionalist” in that they tolerate local culture as long as it doesn’t contradict Islamic teachings. By contrast the second largest Islamic organization in Indonesia, the Muhammadiyah, is considered “reformist” as it takes a more literal interpretation of the Qur’an and Sunnah.

The NU exists to spread Islamic teaching. As well as preaching, it undertakes educational activities through its network of 6,830 Islamic boarding schools, or pesantren. It also owns 44 universities, and is involved in economic and agricultural studies, and social activities including family planning. Its goal is “to spread messages about a tolerant Islam in their respective countries to curb radicalism, extremism and terrorism,” which, it claims, “often spring from a misinterpretation of Islamic teachings.”

According to wikipedia