In Arabic-speaking countries, madrasa or madrassah (place of study) is the word for any institution of education. In other countries, a madrasa is usually a school where people go to learn about Islam.
Other subjects can be studied as well. Across Muslim communities, there are many different kinds of madrasas.
In the historical Muslim world, a network of madrasas taught Islamic law as well as other subjects.
This photo shows a graduation ceremony at a madrasa in Nigeria.
Text adapted from English Wikipedia, Creative Commons Attribution-ShareAlike License 4.0.
Abubakar Siddiq Islamic Foundation First Qur'anic Graduation 07 by AB-Babayo on Wikimedia Commons, CC-BY-SA 4.0.