What is XHTML?

• XHTML stands for EXtensible HyperText Markup Language
• XHTML is an extension of HTML as an application of the XML language
• What is XML?
  • XML stands for EXtensible Markup Language
  • XML is a language that allows information and services to be encoded with meaningful structure. It is geared towards information exchange
  • XML allows the definition of your own tags and attributes
  • HTML is designed for visual presentation. XML is designed to specify data structure and make data independent of presentation
  • XML has full international support via the Unicode character set

• Rules for XML
• XML must be well-formed: it must meet specific criteria
• XML must have one root element
• There can be no space character in the element name or attribute name
• Elements must be correctly nested and closed
• XML is case sensitive
• All attributes must be enclosed in quotes

• Writing XHTML is writing XML code but with a predetermined set of elements
• XHTML documents stress logical document structure
• CSS is strongly encouraged for presentation
• There are two implementations of XHTML: strict and transitional. Transitional works in older browsers. Strict will only work in new ones (e.g. Firefox, Internet Explorer 6/7 Netscape 6/7)

XHTML Rules