The entire CKEditor core code (and most of its plugins) we'll be running inside a single reference object, the CKEDITOR namespace.This object will be available in the page running the editor, and no other variables will be defined in the page by our code.
Inside the core code, the CKEDITOR namespace will be then fragmented in further namespaces, which will group the code resources in specialized blocks. Some examples are CKEDITOR.dom, CKEDITOR.env and CKEDITOR.ui.
Namespaces will mainly hold objects and classes, but it is also allowed to have properties and functions on it. For example, CKEDITOR.env.ie returns a Boolean value, while CKEDITOR.dom.document points to a class