The DOM, a W3C standard since 1998, is a programming interface that lets developers create and modify HTML and XML documents as sets of program objects, which makes it easier to design Web pages that users can manipulate. The DOM defines the attributes associated with each object, as well as the ways in which users can interact with objects. DHTML works with the DOM to dynamically change the appearance of Web pages. Working with the DOM makes Ajax applications particularly responsive for users.

JavaScript Released in 1995 by Netscape and Sun, JavaScript interacts with HTML code and makes Web pages and Ajax applications more active. For example, the technology can cause a linked page to appear automatically in a popup window or let a mouse rollover change text or images. Developers can embed JavaScript, which is openly and freely available, in HTML pages. Ajax uses asynchronous JavaScript, which an HTML page can use to make calls asynchronously to the server from which it was loaded to fetch XML documents. This capability lets an application make a server call.