Like most other filesystems , the Mac OS X filesystem is conceptually a hierarchical tree-based structure that branches from a root. In the case of Mac OS X, the filesystem is rooted on the drive partition from which the system boots. In the typical case where you boot off the single partition of the hard drive that is in your machine, your filesystem is rooted there. If you have more than one disk drive, then the filesystem is rooted on whichever partition you boot from. Likewise, if you boot from an external disk drive or even a disk image on a network server, the filesystem will be rooted from there. Figure 3-2 shows a Finder window displaying the boot disk’s filesystem.
The structure of the Mac OS X filesystem at the root level is very strict, and almost every file that Mac OS X needs to run has a specific place within it. Some of the folders at the root of the filesystem are visible in the Finder when you click on your boot drive; others are not.
Figure 3-2. The Finder showing the boot disk
The folders at the root of the filesystem that are visible in the Finder are:
This folder contains applications that are available to all users on the system. Most applications that Apple ships for Mac OS X (such as iCal, iPhoto, and Safari) are located here. In addition, a large number of useful utility programs, such as the ...