Generic File Icon
This is a generic file, that is, one that doesn't have
any application ownership information stored in the Mac
file system or its own resource fork. Opening
these files typically results in the
TeachText or SimpleText application being used.
Generic Folder Icon
This is a standard folder icon on the Macintosh. Folders
can contain just about anything, including files,
applications and other folders. Opening a folder results
in the contents of that folder being displayed in a
separate window on the Macintosh.
System Folder Icon
A special folder at the top-most level of the boot disk
on the Macintosh is the System Folder. It
contains all the files, applications, and information
needed to run and maintain the Macintosh operating
system itself. The "X"
inside the folder icon indicates that this
particular System Folder is live and that
the information inside was used to actually start up
the current Macintosh.
Applications Folder
All of the major applications in Mac OS X live in a shared
folder called the Applications Folder. It's easily
recognized by the 'A' on the folder icon itself and is
the first place to look when you seek any of the many
Macintosh applications included with the operating system.