A collection of functions, somewhat like Javascript statements, that can manipulate the data within the object, but cannot manipulate anything outside of the object. Functions that belong to an object are called methods of the object. Methods resemble the procedures or routines in older computing languages. A display area of some kind, usually consisting of some piece of the screen on which a button, window, or pop-up menu is drawn. Objects which do have a visible display are called display objects .
Some objects are capable of accepting input from the user.
These are called interactive objects . The idea is that an object is a sealed box. Only the methods belonging to an object can access and manipulate the property data which belong to that object. If you want to know about the properties in a object, or change them, you have to send a message to one of the methods in that object. The message activates that method.