Browser software contains built-in objects. You can access these objects, along with their properties and methods, when building your Web applications.
This hierarchical collection of objects follows a standard referred to as the Document Object Model (DOM).
The World Wide Web Consortium (http://www.w3c.org) is responsible for setting the standards for the DOM.
The DOM is built into the browser software. Using client side scripting, programmers can access all of the objects, properties, and methods within the DOM.