What are the four layers of Mac OS X, from bottom to top?

1. Core OS or Darwin layer – foundation of OS, responsible for all Input/Output and for managing memory and processor usage

2. Core services Layer – includes Quartz (graphics engine), QuickTime, Directory Services, as well as others

3. Developer Frameworks (Carbon, Cocoa, Java 2)

4. Application Layer – where the user interacts with the Macintosh