Web development can take different forms, from a simple static page to dynamic page with a connection to a database.
HTML or XHTML
Any web page includes a basic HTML or XHTML. It is a markup language that essentially defines the structure of the web page (titles, tables, paragraphs, etc..).
It is a language that lets you create hyperlinks, ie links from one document to another or from one place in a document to another location in the same document.
This language is defined as the structure of the page, with added tags that are involved in shaping the document format.
Since version 4, HTML is accompanied by CSS (Cascading Style Sheets) which are styles that are responsible for formatting the page.
XHTML is an evolution of HTML based on XML.
Limitations of HTML
A web page created in HTML is completely static and provides little opportunity for interaction with the visitor. Each page must be created in advance and must be manually updated.
On the dynamic pages, there are only few HTML tags, but the owners not recognized by the W3C.
Some features of CSS allow to create some momentum in the page (eg, color change when hovering). CSS 3.0 is changing the game.
As for the interactivity, HTML can only create the bottom of a form of interaction with the visitor. It allows you to define the parameters of an action, and send the form data to a ”system” that will manage them, but does not define the action itself.
HTML is multiplatform. All web browsers recognize the basic HTML, only certain tags are specific to certain browsers (such as <marquee> tag that is interpreted as scrolling text in Internet Explorer). CSS, even if they are standardized by W3C, are not always recognized in the same way by different browsers.
HTML has the advantage of being easy to implement, and requires no special technical skills. Its pages are a very light and fast processing by the server.
So you have something new to add animation and interactivity on the web page.
XML (eXtended Markup Language)
The XML markup language can also be the basis for a web page. The XML file will contain the content of the web page. This file will be linked to an XSL (XML Style Sheets) which will form the data in the XML file.
Most of the time, the web page will not be based on a native XML file, but it will be dynamically generated by the web programming languages.