The DOM

DOM
The Document Object Model (DOM) is an API for manipulating HTML and XML documents. It provides a structural representation of the document, enabling you to modify its content and visual presentation by using a scripting language such as JavaScript.
https://developer.mozilla.org/en-US/docs/DOM


The Document Object Model (DOM) is a cross-platform and language-independent convention for representing and interacting with objects in HTML, XHTML and XML documents.[1] Objects in the DOM tree may be addressed and manipulated by using methods on the objects. The public interface of a DOM is specified in its application programming interface (API). The history of the Document Object Model is intertwined with the history of the "browser wars" of the late 1990s between Netscape Navigator and Microsoft Internet Explorer, as well as with that of JavaScript and JScript, the first scripting languages to be widely implemented in the layout engines of web browsers.
http://en.wikipedia.org/wiki/Document_Object_Model

DOM elements
http://ejohn.org/blog/html-5-data-attributes/