C # Register function using Windows API to call back whenever key is pressed

Question

How can I use Windows API in C# to register a call back function to be called whenever key is pressed?

Answer 1

A simple google search brings up this promising solution:
Processing Global Mouse and Keyboard Hooks in C#

and even a search here on StackOverflow brings you (beside many others) to: Global keyboard capture in C# application which leads to Low-Level Keyboard Hook in C#.

So where was the big problem in searching this on yourself?