Cocos2D is a family of 2D / 3D API’s, used to create games and applications. The family members are:
The Old One
Cocos2D-ObjC was originally called Cococ2D-iPhone, and became famous when the Apple App-Store was introduced. As the name implies, Cococs2D-ObjC is based on Apple’s Objective-C language, and is the version you are currently visiting. A special version named Cocos2D-spritebuilder, features a WYSIWYG editor, and Android cross platform capabilities.
The Big One
Cocos2D-x started as a C++ fork of iPhone, and has since grown to become the largest member of the Cocos2D family. The guys behind Cocos2D-x (The so-called X-men), provides cross platform to Android, Windows and many other plaforms, as well as all the tools needed.
The Original One
Cocos2D was originally developed in Python, and is still alive.