Mac OS X Technologies

I decided to read the Mac OS X Technology Overview.  It is an overview of the technologies and systems that Mac OS X uses.  I don't understand it all, but it is giving me a good overview of what I am going to be working with when I program with Objective-C.  I read about the underlying frameworks and the Mach kernel.  There are several Core frameworks that I will be using, such as Core Image to create the windows in my applications and display everything that I will need.  I am almost finished reading through that and then I will go back to the Objective-C document and begin trying out some applications myself.