HTML and XHTML are both markup languages used for creating web pages, but they have some differences in syntax and rules.
HTML (Hypertext Markup Language) is a markup language used to create and structure content for the web. It is an SGML (Standard Generalized Markup Language) application and follows SGML syntax rules. HTML documents are interpreted by web browsers to display web pages.
XHTML (Extensible Hypertext Markup Language) is also a markup language used to create web pages. It is an XML (Extensible Markup Language) application and follows XML syntax rules. XHTML is designed to work well with other XML-based technologies like SVG and MathML. XHTML documents are also interpreted by web browsers to display web pages.
Some of the differences between HTML and XHTML include:
- Syntax: HTML has a more relaxed syntax compared to XHTML, which has a stricter syntax. HTML allows certain elements to be left unclosed, while XHTML requires all elements to be properly closed.
- Case Sensitivity: HTML is case-insensitive, while XHTML is case-sensitive. In XHTML, all tags, attributes, and values must be written in lowercase.
- Quoting Attribute Values: HTML allows attribute values to be quoted with either single or double quotes, while XHTML requires attribute values to be quoted with double quotes.
- Entity Declarations: In HTML, some special characters can be represented by named entities like , while in XHTML all special characters must be represented by entity references like &.
- MIME Type: HTML documents are served as text/html MIME type, while XHTML documents can be served as either application/xhtml+xml or text/html.
It’s worth noting that HTML5 is an evolution of HTML that is designed to work well with modern web technologies and devices, and it has many features that were inspired by XHTML. However, HTML5 is still an SGML application, so it does not follow XML syntax rules like XHTML.