No, it's not something to spray on your windshield....
Actually the product is called cygwin, the composition of the names Cygnus, GNU, and Windows. cygwin is a Linux interpreter, or shell, that runs right inside most versions of Window. It does this by firing-off a DLL.
If you are interested in trying out a UNIX-like environment (Linux) on your windows PC without installing another operating system this may be a way to go.
And it's FREE!
I will be installing it and trying it out over the next few days, and if there is anyone out here in cyber-land who might have an interest I’ll keep you posted as to what’s involved in making a successful installation and what to look forward to.
I might even throw in a few UNIX lessons to boot to help you get familiar with cygwin if there is an interest.