For me, XHTML is more natural, because it requires beginning and endings of most elements In the case of the empty elements, the / signals its end. For start and end tags, be aware that many tags are optional. In the 1990s, there was HTML. will not tolerate this incorrect usage, and any document that uses an ampersand incorrectly will not be "valid", and consequently will not conform to this specification. Provide instructions to help users understand how to complete the form and use individual form controls. When using the min attribute, ensure this minimum requirement is understood by the user. Enforce will not be the answer but I think encourage things like always close tags and do not suppress default arguments helps (again, a lot) on the readability of the code. ' to work as expected in HTML 4 user agents. For a document to be valid XHTML, attributes cannot be minimized. Conceptually its possible, but in practice, it should never be done. CSS style sheets for XHTML should use lower case element and attribute names. And coming from the old days of XHTML .. (been away from web design for 5 years) consciously decided now not to close tags if not needed so as to pay more attention. in SGML. Don't include more than one isindex element in the document head. When processing content, user agents that encounter characters or character entity references that are recognized but not renderable may substitute another rendering that gives the same meaning, Therefore, in XHTML 1.0 the id attribute is The following example shows the difference