An XHTML file is a web document written in Extensible Hypertext Markup Language, combining HTML’s flexibility with XML’s strict syntax rules to produce well-structured, consistent, and error-free pages.
Unlike traditional HTML, XHTML enforces a more disciplined coding approach, making documents readable by humans and processable by machines. This is especially valuable for applications requiring precise data and cross-platform compatibility.
Key Features of XHTML:
Doctype Declaration: Starts with a proper DOCTYPE, specifying the version and guiding browsers on interpretation.
File Extensions: Usually saved with .xhtml or .xml to differentiate from standard HTML files.
XML Compatibility: Must follow XML rules like proper nesting, case sensitivity, and closing tags.
Stricter Syntax Rules:
- All tags are properly closed.
- Elements are correctly nested.
- Attribute values are always quoted.
- Tags and attributes are in lowercase.
Root Structure: An XHTML document must have a single root element (<html>) that contains all other elements in a logical hierarchy. In simple terms, XHTML is a cleaner, more disciplined version of HTML aimed at enhancing code quality, consistency, and compatibility with modern web technologies.