Document Object Model (DOM) :
A web browser request for a web pages to a server. The Server delievers the web pages based on the request of web browser. This is a simple request response flow.
Web pages are nothing but the html documents and their is a need of the structured representation of the document. So DOM Provides a structured representation to our html document. Using this we can modify our webpages.
The DOM provides a representation of the document as a structured group of nodes and objects that have properties and methods.
And this representation is object oriented and it can be modified with a scripting language.
For DOM we have standard W3 Representation.
All of the properties, methods, and events available for manipulating and creating web pages are organized into objects (e.g., the document object that represents the document itself, the table object that implements the special HTMLTableElement DOM interface for accessing HTML tables, and so forth).
API (HTML or XML page) = DOM + JS (scripting language)
Important Data Types : document, element, nodeList is an array of elements like the method document.getElementsByTagName() ,attribute
The following is a brief list of common APIs in web and XML page scripting using the DOM.