KOHA is the first and MOST WIDELY USED open source LIBRARY MANAGEMENT SYSTEM
Koha is the first and most widely used open source library management system
Disclaimer
While Prosentient Systems provides Koha hosting we do not represent the Koha community. It is represented by a diverse group of Koha hosting providers and Koha libraries around the world. Koha's community home page can be found at www.koha-community.org