Aqua Guides

In simple terms, Aqua is what a user experiences when he or she uses Mac OS X.  Aqua governs the appearance and behavior of Mac OS X.  Aqua is the intuitive, elegant, and gorgeous graphical user interface (GUI) that Mac users interact with on thier Mac use to accomplish tasks.
In Mac OS X the Desktop is the area of the screen where your work begins.  After you turn on and log into your Mac you are taken directly to the Desktop.  When there are no open application windows running or those active windows have been hidden, you will see something similar to the following on Mac OS X Leopard.
After you run Setup Assistant the first time you boot your Mac, the Mac OS X Desktop is launched.  You'll immediately see a transparent strip of icons located at the bottom of the screen , this area is called the Dock.
Your Dock Your Customizations
Apple starts you off with a pre-configured Dock.  For some users this is sufficient but  for others, they wish to configure it to suit their unique needs.  Thus, if you want to take your Mac OS X experience to another level, customize the Dock.  No two customized Docks are identical.  The focus of this guide is the Dock Behavior and effects.
You can change the default Aqua look and feel something much less vibrant and colorful.  If the bright blues, and the red, green, and yellow window buttons are not your forte, you can change all those elements to gray.
Mac OS X is capable of presenting to the user various icons.  Icons play a vital role throughout the operating system, in application windows, and within applications (programs).  Icons are simply symbols or graphics used to represent an entity with a particular program, window, or option.
When you preform certain desktop actions Mac OS X will play a short sound that lasts only a fraction of a second.