xhtml+css= website Refactoring

One, what is the Web standard?
Web standards are not a standard, but a collection of standards. The Web page consists mainly of three parts: structure (Structure), performance (presentation) and behavior (Behavior). The corresponding standard is divided into three aspects: the structured standard language mainly includes XHTML and XML, the performance standard language mainly includes the CSS, the behavior standard mainly includes the object model (such as the ECMAScript), and so on. Most of these standards are drafted and published by the consortium, as well as standards developed by other standards organizations, such as the Association standard for ECMA (European Computer manufacturers ECMAScript). Let's take a quick look at these standards:
1. Structure Standard language
(1) XML
XML is shorthand for the extensible Markup Language (extensible Identification language). It is currently recommended to follow the XML1.0, a reference (HTTP://WWW.W3.ORG/TR/2000/REC-XML-20001006) published by the Consortium on October 6, 2000. Like HTML, XML is also derived from SGML, but XML is a language that defines other languages. The original design of XML was designed to make up for the lack of HTML, to meet the need of network information release with powerful extensibility, and later to be used to transform and describe the network data. About the benefits of XML and Technical specification details here is not much to say, the internet has a lot of information, there are many books can refer to.
(2) XHTML
XHTML is the abbreviation for the extensible Hypertext Markup Language Extensible Identification language. Currently recommended to follow is the XML1.0 (reference HTTP://WWW.W3.ORG/TR/XHTML1) recommended by the consortium on January 26, 2000. XML is a powerful alternative to HTML, but it is too early to use XML directly in the face of thousands of existing sites. So, on the basis of HTML4.0, we extend it with the rules of XML, and get XHTML. Simply put, the purpose of creating XHTML is to implement the transition from HTML to XML.
2. Performance Standard language
CSS is the abbreviation for cascading style sheets cascading style sheets. Currently recommended to follow is the CSS2 (reference http://www.w3.org/TR/CSS2/) recommended by the consortium on May 12, 1998. The goal of creating CSS standards for the consortium is to replace HTML tabular layouts, frames, and other expressive languages with CSS. The combination of pure CSS layout and structured XHTML can help designers separate appearance and structure, making site access and maintenance easier.
3. Standards of Conduct
(1) DOM
DOM is an abbreviation of the Document Object model. Based on the http://www.w3.org/DOM/, Dom is an interface with browsers, platforms, and languages that allows you to access other standard components of a page. Simply understood, Dom solves the conflict between netscaped JavaScript and Microsoft JScript, giving web designers and developers a standard way to access data, scripts, and presentation layers in their sites.
(2) ECMAScript
ECMAScript is a standard scripting language (JAVASCRIPT) developed by ECMA (European Computer Manufacturers Association). Currently recommended to follow is ECMAScript 262 (Http://www.ecma.ch/ecma1/STAND/ECMA-262.HTM).