(1) A Web page that is customized for each user.  See 
dynamic Web page.
(2) (Dynamic HTML)  A combination of Web technologies for creating menus, interactive dialogs, animations and dynamic Web pages.  The major elements are the ECMAScript language and DOM object model.  ECMAScript is a derivative of JavaScript, and DOM is an interface that presents the data in an HTML document as a data record to the programmer for ease in updating.  See 
ECMAScript, 
DOM and 
dynamic Web page.