Most business websites these days are dynamic meaning that the web pages are dynamically built pages that allow user interaction. This might be used for a forum, shopping cart or other data that is loaded on the fly.
They are usually built with a programming language such as ASP, PHP or JAVA. This code "creates" the HTML that is displayed in the browser. XHTML and XML are standards which are probably eventually replace HTML. However most sites are still "output" in HTML because this is visible in most browsers.
Dynamic sites are often database-driven. This means that the site content is stored in a database and the dynamic code "pulls" the content from a database.
The web technologies listed below - are the most commonly used programming languages for building dynamic websites: