XHTML stands for extensible HyperText Markup Language (extensible HTML) and, like HTML, is a text-based markup language (markup: award) that is used primarily for websites. XHTML is a reformulation of HTML 4.01 in XML and complies with the stricter XML rules.
In addition to the actual content that should be displayed on a web page, an XHTML file also includes awards for how something is displayed and structured. For example, XHTML also integrates images on the website and determines which text is a link and where it should lead.
Generally, you can open XHTML files with any text editor. For better readability you should use a text editor with programming language recognition (eg Notepad ++) or use a real website editor. Xhtml files can also be opened and edited with Microsoft Word or OpenOffice.Org Write, but this is not recommended.
To have an XHTML file displayed as a web page, a modern web browser is sufficient. Embedded files, such as images, must be in the correct location at the location referenced in the XHTML file.
Sometimes the extension xhtm is used, but it identifies the same file type. The file extension XHTML itself is not a necessary marking, browsers are not dependent on it and recognize XHTML files at the header. Many web editors also use the extension html for XHTML files.
Most often resolving problems with opening XHTML files is very simple. Just install an appropriate program that supports such files. All of the listed programs support XHTML files, but may vary in offered function and purpose. Some programs may be capable only of viewing contents of XHTML files or offer file conversion options, but may not be capable of editing such files.
It is possible that although a compatible program has been installed on user’s system, it is not used by the system to open it. This may happen because no default application was associated with this type of files. To associate XHTML files with given application, select "Open with" from drop-down menu (accessed by right-clicking on the file). Then select from the list the program or application you want to be used to open this type of file. If the Safari applications is not on the list, select "Browse" option in order to manually locate the directory where Safari has been installed.
Sometimes problems with opening XHTML files may not lie with the application itself, but can arise due to other causes, such as: