HTML is HyperText Markup Language, a language derived from SGML (Standard Generalized Markup Language) and used on the World Wide Web to create structure for the presentation of documents and create links between them, using tags and a set of rules. XML is EXtensible Markup Language and simplified SGML. XHTML is EXtensible HTML, a markup language that combines features of HTML and XML, with stricter rules than those applied in HTML coding. An XHTML editor is an environment designed for authoring XHTML.
An XHTML editor is not usually found as a stand-alone product. It is quite common to find an XHTML editor incorporated in a product that provides a more comprehensive package of web development editors. For example, a software package might combine and XHTML editor with an HTML editor. A more complete package could include an HTML editor, XHTML editor, CSS (Cascading Style Sheets) editor, and JavaScript editor.
XHTML editors often have both a text editor in which to input XHTML and a WYSIWYG (What You See Is What You Get) editor, and sometimes it’s possible to show only the WYSIWYG window. The purpose is to allow a user who hasn’t learned the technical aspects of web design, such as markup languages and CSS, to still be able to generate and edit content. However, one problem with web pages and websites being built with correct XHTML has been WYSIWYG editors that do not generate proper markup. XStandard points out the problem and makes XHTML WYSIWYG Editor™ to address this, assuring that only markup that meets best practice criteria is used.
One important feature you may find in an XHTML editor is the ability to choose the version of XHTML you are working on. Adobe Dreamweaver CS4, for example, offers a choice of XHTML 1.0 Transitional, XHTML 1.0 Strict, XHTML 1.1, or XHTML 1.0 Mobile. HTML 4.01 Transitional and HTML 4.01 Strict are also offered.
In any case, there are some other features that may be present in an XHTML editor. One valuable feature that is not universally offered is XHTML validation. Alternatively, dynamic correction may be offered along with an error log file. An HTML to XHTML conversion feature may also be included. Other desirable features include syntax highlighting, word wrap, and UTF-8 Unicode (8-bit UCS/Unicode Transoformation Format) — UCS stands for Universal Character Set — to enable work on multilingual files.