Recap: Steps for Conversion to XHTML

Add a DOCTYPE Definition, xml namespace, and character set
Lower Case Tag and Attribute Names
Quote All Attributes
Edit Empty Tags: <hr> , and <img> ... [input, meta, link] to use a closing slash : <hr /> , , etc.
Make sure all tags are ended and properly nested (e.g. )
Replace deprecated tags and attributes, and consider updating layout techniques and style.
- A guide to deprecated tags can be found at: http://www.kevinhatch.com/webdev/xhtml/deprecated.php
- A list of valid xhtml tags can be found at: http://www.w3schools.com/xhtml/xhtml_reference.asp
- Many of the deprecated tags are used for presentation (e.g. ).
- The new standard for presentation and control of visual display is Cascading Style Sheets (CSS), which are useful for keeping style separate from content. Although many old formatting techniques are still supported under xhtml transitional, it is a good idea to move over to Cascading Style Sheets.
 - The tags and , although they are not deprecated, should be replaced with and , as and are merely presentational and are not universally interpreted as adding emphasis to the text to which they are applied.
Use The W3C MarkUp Validator to see if anything was missed
An XHTML document is validated against a Document Type Definition (DTD). Before an XHTML file can be properly validated, a correct DTD must be added as the first line of the file.