DHTML Dynamic HyperText Markup Language) can't really be considered as a markup language for the Internet and also there's no standard fully defining it. DHTML refers to a set of related Internet technology to provide more interactive HTML pages, that is to say, the content can be changed through events (mouse movement, mouse over, ...), after the loading the page.
The implementations of DHTML are:
The HTML used to present documents;
Style sheets (CSS) to define a style for multiple objects and their position on the page;
The Document Object Model (DOM), suggesting a hierarchy of objects to facilitate their manipulation;
The use of "dynamic" HTML pages is only possible on the latest web browsers and sometimes the interpretation of HTML code can be different from one browser to another. To make sure that the effect will be seen on the majority of configurations, it may be needed that you:
write a script for each browser;
create (if possible) a script running on different browsers.