What is System in rhinopython editor

I try to read samples in rhinopython, but I don’t know the meaning of “import System” or “from System.Windows.Forms”
where we can find the folder of “System”?
I know we can import rhinoscript outside Rhino, such as in Pycharm, but how I can import System in Pycharm?

System is a .NET namespace


The System namespace is from the System.dll assembly included with the .NET Framework.

Keep in mind that Rhino uses IronPython, not CPython…

– Dale

very helpful, thanks!