NHibernate is an object-relational mapping (ORM) solution for the Microsoft .NET platform: it provides a framework for mapping an object-oriented domain model to a traditional relational database. Its purpose is to relieve the developer from a significant portion of relational data persistence-related programming tasks. NHibernate is free as open source software that is distributed under the GNU Lesser General Public License. NHibernate is a port of the popular Java O/R mapper Hibernate to .NET.