Outlets are instance variables that are declared using the keyword IBOutlet. A declaration of an outlet in your controller's header file might look like this:

IBOutlet   UIButton   *myButton;

The IBOutlet keyword is defined like this;

#ifndef IBOutlet

#define IBOutlet

#endif

This actually does nothing as the compiler is concerned. This acts as a hint to tell the interface Builder that this is an instance variable that we're going to connect to an object in a nib. Any instance variable that you create and want to connect to an object in a nib file must be proceded by the IBOutlet keyword. When you open interface builder , it will scan your projects header files for occurances of this keyword and will allow you to make connections from your code to the nib based on these variables.