When the Web was first created, most websites were static, which means that their content was always the same no matter what the user did. As websites began to get more complicated in both content structure and design, the need to create pages that could react and change depending on user input became more important. This need is why DHTML started to be used by programmers.
It is impossible to say exactly when DHTML script was first used, but it did start to gain in popularity when Version 4 browsers were released. A familiar problem for Web designers is that it is difficult to use new technology since users on the whole are relatively slow to upgrade their browsers. This fact delayed the use of DHTML script. Use of DHTML script began to really take off when the World Wide Web Consortium (W3C) released a set of standards for its use. This allowed Web designers to create standardized scripts that could be used across the Internet.
DHTML works by allowing the owner of a website to create variables that can be changed by the end user. These variables affect the HTML code of the page, which in turn changes the way the website appears to the user. The important distinction to make between DHTML and other scripting and Web development languages is that DHTML cannot change the page to unique content every time a page loads. Instead, it can only change the way the page appears after it has been loaded.