Objective-C is a reflective, object-oriented programming language that adds Smalltalk-style messaging to the C programming language. Today, it is used primarily on Apple's Mac OS X and iOS: two environments based on the OpenStep standard, though not compliant with it.Objective-C is the primary language used for Apple's Cocoa API, and it was originally the main language on NeXT's NeXTSTEP OS. Generic Objective-C programs that do not utilize these libraries can also be compiled for any system supported by gcc or Clang.