ReactOS is an Open Source effort to develop a quality operating system that is compatible with Windows NT applications and drivers.

License
ReactOS is licensed under the GNU General Public License.

Relationship with the WINE project
ReactOS has always planned to work with the WINE project to share as much programming effort as possible.
This will mainly concern User Mode DLLs and will happen once ReactOS's Kernel Mode areas are more complete, as those areas form the underlying infrastructure. Other areas of cooperation lie in applications and testing suites.

Future compatibility
The ReactOS project, although currently focused on Windows NT 4.0 compatibility, is always keeping an eye towards compatibility with future Windows NT releases, that is, Windows 2000 (NT 5.0) and Windows XP (NT 5.1).

Supporting other System Applications
The Windows NT architecture allows for subsystems, as does the ReactOS architecture. A subsystem is an implementation of the APIs of another operating system, allowing ReactOS to run applications from other systems. We are already looking at subsystems for: Java, OS/2 and DOS and possibly others in the future.