XHTML is the most recent version of HTML. It reformulates HTML in terms of XML, bringing greater regularity to the language as well as an increased separation of logical structure from the presentational aspects of documents.
Notice how the script is included directly in the markup using the <script> element that encloses the simple one-line script:
Regardless of whether or not the error was displayed, to output the string properly we could either include the <strong> element directly within the output string, like so,
or we could surround the output of the <script> element in a <strong> element like this:
Readers looking for more information on correct HTML and XHTML usage should consult the companion book HTML &XHTML: The Complete Reference, Fourth Edition by Thomas Powell (McGraw-Hill/Osborne, 2003).