The folder on a disk which contains all of the system software on a Macintosh.

The System Folder contains the system software, which the Mac uses to boot, manage files, run programs, manage network connections, and so on. Any configuration files will be located there. The Apple Menu Items as well as Control Panels are located there also.

an all important folder that contains the System files

The System Folder usually located at the top level of the Startup Disk, is a folder that contains the currently running Operating System. This software controls how the computer talks with its components such as the keyboard, disk drive, and printer; and it manages things such as memory and network control. The System Folder can have items added to it so that it can be extended personally by the operator. The System Folder will typically have an Icon with a small Mac on it.

the folder that contains your System software

The System Folder is the directory in classic versions of Mac OS (those prior to OS X) that holds various files required for the system to operate, such as fonts, system extensions, control panels, and preferences.