Cocoa Cocoa is a modern, object-oriented framework Cocoa contains the class definitions for classes that are generally useful to produce a graphical user interface (GUI) for applications to be run under Mac OS X. Cocoa also provides an object-oriented interface to the operating system (OS). Cocoa is what Apple itself uses to develop Mac apps for Mac OS X. You are able to harness the full power of a Macintosh by using Cocoa.
Programming using Cocoa involves both using a graphical user interface (GUI -- pronounced "gooey") tool to build your user interfaces, and an integrated development environment (IDE). Cocoa consists of literally hundreds of ready-built classes, functions and constants, which are pre-programmed modules of reusable code, that you can simply include in your own work and build upon. Since these classes are well designed, powerful and fully debugged, using them saves you literally hundreds of hours in building in complex functionality.
Cocoa is the name given to the complete set of classes, functions and constants, grouped together into an Application Programming Interface, or API. For building Mac applications Cocoa is the only API that is really used anymore. (The other APIs that used to be provided by Apple, the Classic API and the Carbon API which have both been deprecated.)
Above all, this text aims to get you started in the smoothest way possible, so that you can begin to see not just how powerful Cocoa can be, but also how rewarding it is to work with.