HTML (Hypertext Markup Language)

HTML is like the language that web browsers understand. It’s used to create the structure and content of web pages.

Think of it as the backbone of a webpage. In HTML, you use tags (like ) to define different elements such as headings, paragraphs, images, links, and more. HTML is forgiving in the sense that it doesn’t always require perfect syntax and structure to work properly in web browsers.

XHTML (Extensible Hypertext Markup Language):

XHTML is an evolution of HTML. It follows the same basic rules as HTML but is stricter about how the code is written. Think of XHTML as a bit more disciplined version of HTML. It enforces rules about properly nested tags, lowercase tag names, and attributes being enclosed in quotes. This strictness makes it easier for web browsers and other tools to process the code consistently.

Key Differences of HTML & XHTML:

Syntax Strictness: XHTML is more strict than HTML. It enforces proper structure and syntax more rigorously. This can help catch errors early and make sure pages display more consistently across different browsers.

Case Sensitivity: XHTML is case-sensitive when it comes to tag names and attribute names, whereas HTML is generally case-insensitive.

Quoting Attributes: In XHTML, attributes must be enclosed in double quotes (like attribute="value"), while in HTML, single quotes can also be used (like attribute='value').

Self-Closing Tags: XHTML requires that self-closing tags (like <img /> for an image) have a space before the closing slash (<img />). In HTML, it’s acceptable to just use <img>.

Conformance to XML: XHTML is designed to work well with XML, which is a more strict markup language. This can make XHTML documents easier to integrate with other XML-based systems.

Error Handling: HTML is more forgiving of errors, often rendering pages despite issues in the code. XHTML is less forgiving and might not display content properly if the code has errors.

Compatibility: Since XHTML is stricter, it might require more attention to detail when converting existing HTML pages to XHTML. Also, some older browsers might not handle XHTML well.

In summary, HTML and XHTML are closely related, but XHTML imposes stricter rules on how your code is written. It’s like HTML with a bit more discipline, and it’s designed to work better with other XML technologies. However, modern web development tends to use HTML5, which has some features of both HTML and XHTML and is more widely supported.