The Document Object Model (DOM) describes the structure of an HTML document and the relationship between its elements. The DOM represents the page as nodes organized in a tree structure. Nodes can be elements, attributes, and text. Elements are parent nodes that can have child nodes, and elements on the same level are siblings. The DOM provides access to elements via methods like getElementById, getElementsByTagName, and by accessing named form elements through the document.forms object.

1. Document Object
Model
DOM

2. WHAT IS THE DOCUMENT OBJECT MODEL (DOM)?
• The DOM is and acronym for Document Object Model.
• its job is to describe the structure of a HTML document and the
relationship between different elements like tags, attributes, and texts on
a page.
• As you add, delete or modify existing elements on your website, you're
creating structure that a browser interprets as the DOM.
• The DOM is also the API that gives languages like JavaScript and CSS a way
to define and modify the existing document.
• It's really best to think of the DOM as an upside down family tree.
• Every element in the DOM, including the text and attributes are
considered nodes.
• Nodes can be both parent, and have children elements.
• Elements in the same level is known as siblings.
• The first and last children of an element have special names called first
child and last child.
• The rest of the children of the element are known as child nodes.

3. SELECTING ELEMENTS WITH GETELEMENTBYID
• It allows you to select and element in the HTML file
that is a tag that has a single ID attribute.
• getElementById() expects to find only one ID since an
ID should appear only once in each document.

4. CHOOSING ELEMENTS BY HTML TAG
• Traditionally, the easiest way to get to an element is by
ID, but you probably don't have an ID for every
element in the DOM.
• If getElementsByID is the most popular way to access
things, then getElementsByTagName is the next most
popular.
• GetElementsByTagName lets you access elements by
their HTML tags.
• It's super simple to use and returns an array.

5. WORKING WITH NAMED FORM ELEMENTS
• Selecting form elements is a little easier because forms
can have and additional attribute called Name.
• The DOM provides a special object called
document.forms.
• That's an array of form elements on the page.
• You can also get to any form element that has a name a
little bit easier.
• If I want to get into that element, I can say document
forms and then the index.