Let's pause and review. We know that JavaScript has objects, which are like nouns or things. We know that objects have properties that describe how objects look, just as adjectives describe nouns. We refer to properties as object.property . We also know that objects have methods, or actions that can be performed to the object.
Different objects have access to different properties and methods.
Now we'll learn the secret to understanding JavaScript, the Hierarchy of Objects . Windows and frames both belong to the Window object. Top, self, parent, and frames are built-in names for windows. Don't worry too much about these. Just know they exist.