# Converting HTML files to XHTML files

The Extensible HyperText Markup Language (XHTML), a set of document types that rework the HTML code using XML, is the successor of HTML. To take advantage of the specifications that have been developed for XHTML, you can convert existing HTML pages to XHTML pages.

To convert an existing HTML file to an XHTML file, complete the following steps:

1. Select Tools > Convert to XHTML.
2. Typically, you should accept the Insert XML declaration check box default in the Convert to XHTML dialog box. In addition, you should select the appropriate XHTML document type from the list box.
3. Click OK.

   A new XHTML file replaces the converted HTML file, though the file extension does not change. You can open the newly created XHTML file in the Source page to verify that the appropriate XML declaration and document type value are reflected.

4. The Convert to XHTML dialog is also available for existing XHTML files, because it may be applicable in the following cases:
   - It can be used to change DOCTYPE declaration from one XHTML DTD to another; for example, from XHTML 1.0 Transitional to XHTML Basic 1.0.
   - It can be used to clean up tags that don't conform to XHTML standards, such as upper case tags in an existing XHTML file.

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