You need to install the .NET Framework to run many apps on Windows, such as tax filing apps and games. The .NET Framework comes from Microsoft and is updated by Windows Update.
The .NET Framework 4.5 and later versions are not supported on Windows XP, but on Windows Vista, Windows 7 and later versions of Windows.
If you need to run an app that requires the .NET Framework 4.5 or later, you will to upgrade to a later version of Windows or find another machine that has a later version of Windows. You can also contact the publisher of the app, to see if they support Windows XP with another version of their app.
The .NET Framework 4 is supported on Windows XP, however, it will not run apps that require .NET Framework 4.5 or later versions.
This information has been provided by the .NET team.