When a web page is loaded, the browser creates a Document Object  Model of the page.

The HTML DOM model is constructed as a tree of Objects:

With the object model, JavaScript gets all the power it needs to create dynamic HTML:

• JavaScript can change all the HTML elements in the page
• JavaScript can change all the HTML attributes in the page
• JavaScript can change all the CSS styles in the page
• JavaScript can remove existing HTML elements and attributes
• JavaScript can add new HTML elements and attributes
• JavaScript can react to all existing HTML events in the page
• JavaScript can create new HTML events in the page

What is the DOM?

The DOM is a W3C (World Wide Web Consortium) standard.

The DOM defines a standard for accessing documents:

“The W3C Document Object Model (DOM) is a platform and language-neutral interface that allows programs and scripts to dynamically access and update the content, structure, and style of a document.”

The W3C DOM standard is separated into 3 different parts:

• Core DOM
• standard model for all document types
• XML DOM
• standard model for XML documents
• HTML DOM
• standard model for HTML documents

What is the HTML DOM?

The HTML DOM is a standard object model and programming interface for HTML. It defines:

• The HTML elements as objects
• The properties of all HTML elements
• The methods to access all HTML elements
• The events for all HTML elements

In other words: The HTML DOM is a standard for how to get, change, add, or delete HTML elements.