HTML is the language of the web. All websites are written with the use of different kinds of HTML. However with the fast evolution of the web, HTML grew rapidly but in an unplanned manner. Those who are not very familiar with the different version of HTML may suffer from some difficulties.

HTML for the very first time was created by Tim Berners-Lee, the inventor of the web. It was based on Standardized General Markup Language. There was no 'img' tag in the first version. This means that no graphics could be added on any web page.

Due to the lack of standardization, problems started to arise as the same page was viewed completely differently in two different browsers. To solve this problem, HTML was standardized as HTML 2. Most of the web browsers were based on it.

HTML 3 and HTML 4 were introduced in the following years to update the standard and remove some of the tags that should not be used. This version of HTML is in use today, other than some minor changed done in 1999.

DHTML
DHTML stands for Dynamic HTML and is the combination of HTML with Javascript and CSS. It means that DHTML is used to web applications, whereas HTML is used for web pages. DHTML techniques are become quite popular as the web is now being used to do many more operations that were earlier done with the use of different programs.

XHTML
XHTML is a version of HTML that follows the XML standards.  eXtensible Markup Language or XML, is a standard for HTML and other similar languages used for many purposes such as sharing of data and configuration.

As compared to the HTML, XHTML is a much more standardized and easier to test option. It points out any existing errors automatically with the use of validators. This feature makes web pages much simpler to maintain and also enables to make the site compatible to a variety of browsers.

There are a number of versions of HTML. The transitional version enables the usage of old HTML4 practices, whereas to get the benefits of XHTML, user need to use the 'strict' version.

Need of different versions of HTML
Before you start building your site, it is very important to decide on the version that you are going to use. Knowledge of all these version is required to know which version would best suit your site the best and on which version would your tools work best.

Presently, XHTML is mostly recommended as it makes the process of website development much simple. However, it is better to use HTML4 or DHTML in case you are designing a web application, and not a web page.