Microsoft Primary Interoperability Assemblies 10.0.30319

PIAs are a set of .NET assemblies provided by Microsoft that contain definitions of a set of interfaces and classes that allow managed code to interact with specific COM objects and their corresponding interop assemblies.

PIAs are important because they provide a way for managed code to communicate with COM objects, which cannot normally be accessed directly by managed code due to differences in how they manage memory.

You will need the appropriate version of the .NET Framework installed, as well as the relevant interop assemblies for the COM object you intend to use.

The PIAs can usually be found in the Global Assembly Cache (GAC) on your system, or can be obtained from the vendor who provided the COM object.

You can add a reference to a PIA using the Visual Studio IDE or by manually editing the project file to include a reference to the PIA.

If you don't have the appropriate PIA installed, your code may not be able to compile or execute properly.

PIAs are compatible with versions of the .NET Framework starting with 1.0 and up through 4.8. Newer versions of the framework may require updated PIAs.

Yes, it is possible to create your own PIAs using the .NET Framework SDK tools, but it is generally not necessary or recommended for most applications.

No, there are no licensing issues associated with using PIAs, as they are part of the .NET Framework and can be freely distributed and used.

Yes, you can usually use a PIA with a non-Microsoft COM object, but you may need to obtain the appropriate interop assemblies from the vendor who provided the COM object.