Cascading 
  Style Sheets: 
  This is a system that separates 
  the content of a page (written in html) from the format
  (written in CSS) and in doing so allows for more complete control over the design 
  of a 
  web page while keeping the page universal. In addition, CSS can be applied to 
  several 
  pages at once, helping the designer save time by storing all the formatting 
  in one file.
Unfortunately CSS does not 
  work in older browser versions. Only in IE version 4 and up 
  and Netscape 4 and up
JavaScript, 
  DOM, and Dhtml:
  Advanced web designers often use a scripting language called JavaScript and 
  a system
  of naming the parts of a Web Page (DOM-Document Object Model) together with 
  html
  and often CSS to create dynamic content on a page. These effects are called 
  Dhtml
  or Dynamic html
XML (Extensible 
  Markup Language):
  Like html it is a system of making tags that web page creators create for their 
  content.
  It. This makes it easier to read for computers and easier to catalog, making 
  it searchable
  by search engines. Ex. <songtitle>Yesterday</songtitle>