The XHTML is a text based file format with markup in the XML, using a reformulation of HTML 4.0. These files are well suited to be open or viewed in a web browser. XHTML was designed to be more structured, less scripting, generic; using all the existing facilities of XML and more device independent. XHTML provides a generally worthwhile set of elements and attributes, with extension options in combination with style sheets.Read More
You can also add signature in other file formats. Please see the list below.