NHibernate is a mature, open source object-relational mapper for the .NET framework. It is actively developed, fully featured and used in thousands of successful projects.
The NHibernate community website - http://www.nhforge.org - has a range of resources to help you get started, including wikis, blogs and reference documentation.
The quickest way to get the latest release of NHibernate is to add it to your project using NuGet (http://nuget.org/List/Packages/NHibernate).
Alternatively binaries are available from SourceForge at http://sourceforge.net/projects/nhibernate.
You are encouraged to review the release notes (releasenotes.txt), particularly when upgrading to a later version. The release notes will generally document any breaking changes.
There are two official NHibernate community forums:
If you find any bugs, please report them using the JIRA bug tracker. A test-case that demonstrates the issue is usually required. Instructions on providing a test-case can be found here.
This software is distributed under the terms of the Free Software Foundation Lesser GNU Public License (LGPL), version 2.1 (see lgpl.txt).
Many thanks to the following individuals, organisations and projects whose work is so important to the success of NHibernate (in no particular order):