| Feature |
HTML |
XHTML |
| Definition |
Hypertext Markup Language is a markup language used to create web pages and other information that can be displayed in a web browser. |
eXtensible Hypertext Markup Language is a markup language that is a stricter version of HTML and conforms to XML syntax. |
| Syntax |
HTML allows for loose syntax, with end tags and attributes often being optional. |
XHTML requires end tags for all elements and attributes to be quoted. |
| Document Type Declaration (DTD) |
HTML allows for multiple DTDs, including HTML 4.01 and HTML5. |
XHTML requires the use of a specific DTD, such as XHTML 1.0 Strict or XHTML 1.1. |
| Namespaces |
HTML does not support namespaces. |
XHTML supports namespaces, allowing for the integration of other XML languages. |
| Attributes |
HTML allows for the use of deprecated attributes. |
XHTML does not allow the use of deprecated attributes and requires all attributes to be lowercase. |
| Deprecation |
HTML will continue to be supported by web browsers. |
XHTML support by web browsers is limited and it is now largely replaced by HTML5. |
| Future |
HTML continues to evolve, with the latest version being HTML5. |
XHTML development has largely been discontinued, with future developments focusing on HTML5. |
