Where does Mac OS X store fonts?

Mac OS X stores fonts in several different places, which can make dealing with fonts a bewildering experience. FontAgent Pro eliminates this confusion by keeping all of your personal fonts in a central, organized location and enabling you to manage system fonts at the same time.
For a font to be available to software applications, it must be loaded into memory. Mac OS X loads fonts residing in any of the folders that appear below into memory when you start your computer. Fonts loaded by the operating system cannot be deactivated.

/Library /Fonts
Fonts in this folder are available to all users who log onto the computer.

<user>/Library/Fonts
Fonts in this folder are only available if <user> is logged in.

/System/Library/Fonts
These are the core System fonts and you should not alter or move them. FontAgent Pro does not manage fonts in this folder.

/System Folder/Fonts
If Mac OS Classic is installed, fonts in this folder are available to all users.