New package format for Win32, Desktop Bridges, and Universal Windows Platform (UWP) applications.
MSIX is a new package specification which provides a unified packaging format for Win32, Desktop Bridges, and Universal Windows Platform (UWP) applications.
MSIX was built from the ground up to deliver complete containerization for Windows 10 applications. The format utilizes the AppX application framework and provides a path to deploy all Windows 10 Applications to the Windows Store. It inherits all the great features in UWP and most importantly, it applies to all Win32, WPF, Windows Forms, and UWP applications.
Importantly this new and in-progress MSIX package format is essentially a major improvement of the current AppX format - rather than the MSI format - despite the name.
Microsoft seems to envision a future where MSIX not only replaces MSI, but also creates a package format which cross-platform Microsoft applications can recognize and use on any platform (iOS, Android, MacOS, and Linux).
MSIX is an emerging technology with little official information currently available. Accordingly the above information has been assembled primarily from the following sources: