How do I detect what .NET Framework versions and service packs are installed?

Question

A similar question was asked here, but it was specific to .NET 3.5. Specifically, I\'m looking for the following:

1. What is the correct way to determine which .N

Answer 1

Update for .NET 4.5.1

Now that .NET 4.5.1 is available the actual value of the key named Release in the registry needs to be checked, not just its existence. A value of 378758 means that .NET Framework 4.5.1 is installed. However, as described here this value is 378675 on Windows 8.1.