In Mac OS X, what is Aqua?

In Mac OS X, Aqua is the graphical user interface (GUI). It controls the appearance and function of windows, menus, icons, and other interface elements. The Finder and the Dock are both displayed through Aqua.

Also see:

• What is Mac OS X?
• In Mac OS and Mac OS X, what is the Finder?
• For Mac OS X, what are Quartz and Quartz Extreme?
• For Mac OS X, what is the Classic environment, and how do I activate it?
• What is iTunes and what does it do?
• At IU, how do I configure Mac OS X Mail to read my Cyrus (Webmail) or Exchange mail through IMAP?
• What is Darwin?