Introduction to the differences between html, xhtml and xml_HTML/Xhtml_Web page production

Development trend:

html (Hypertext Markup Language) - xhtml (Extensible Hypertext Markup Language) - xml (Extensible Markup Language);

html:

1. Insensitive to case;

2. Tags do not have to appear in pairs;

3.
;

xhtml:

1. It is case-sensitive and must be lowercase;

2. Tags must appear in pairs, and if there is a start tag, there must be an end tag;

3. Attribute values ​​must be between quotation marks Within;

4. Attribute minimization is not supported:

eg: Correct:

Error:

5.name attribute The use is deprecated and will be eliminated in the future;

6. Empty elements must also end with tags: such as:
,

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(horizontal dividing line)

xml:

html will eventually develop into xml. xhtml is a transition between html and xml. The characteristics of xhtml are also suitable for xml;