Problem Domain, Objects, and the DOM

I see the crystal raindrops fall and the beauty of it all is when the sun comes shining through - Bill Withers, Just The Two of Us.

Chapter 3: “Object Literals” (pp.100-105)

Objects group together a set of variables and functions to create a model of a something you would recognize from the real world. In an object, variables and functions take on new names.
If a function is part of an object, it is called a method.
If a variable is part of an object, it is called a property. Properties tell us about the object, such as the name of a hotel or the number of rooms it has.
variables and named functions, properties and methods have a name and a value. In an object, that name is called a key.
HTML uses attribute names and values.
CSS uses property names and values.

The Document Object Model (DOM) specifies how browsers should create a model of an HTML page and how JavaScript can access and update the contents of a web page while it is in the browser window.
The DOM is neither part of HTML, nor part of JavaScript; it is a separate set of rules. It is implemented by all major browser makers, and covers two primary areas
The DOM is called an object model because the model (the DOM tree) is made of objects.
As a browser loads a web page, it creates a model of that page. The model is called a DOM tree, and it is stored in the browsers’ memory. It consists of four main types of nodes.
Every element, attribute, and piece of text in the HTML is represented by its own DOM node. At the top of the tree a document node is added; it represents the entire page and also corresponds to the document object,
HTML elements describe the structure of an HTML page. (The < hl> < h6> elements describe what parts are headings; the < p> tags indicate where paragraphs of text start and finish; and so on
Relationships between the document and all of the element nodes are described using the same terms as a family tree: parents, children, siblings, ancestors, and descendants. Every node is a descendant of the document node.
DOM queries may return one element, or they may return a Nodelist, which is a collection of nodes.