Dynamic HyperText Markup Language (DHTML) script is a group of scripting languages used to add interactive elements to websites. DHTML is not a separate language itself — HyperText Markup Language (HTML), Cascading Style Sheets (CSS), JavaScript, and Document Object Module (DOM) are the main languages that make up DHTML script. The dynamic nature of DHTML allows a webpage to change once it has been loaded into a Web browser, but it cannot change the content each time the page is loaded.
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.
One confusing aspect of DHTML script is that it is not considered to be a computer programming language because it is a set of different scripting and markup languages used together — namely HTML, CSS, JavaScript, and DOM. CSS is used to create style sheets that define how a webpage appears, while JavaScript can add the interactive elements. Also, it is not a technique for creating dynamic content, but instead a tool for making a website interactive. This means that it serves a different purpose than other scripting languages, such as Hypertext Preprocessor (PHP).
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.