What are the Html-xhtml-xml, respectively?

HTML: Hypertext Markup Language;

XHTML: Extensible Hypertext Markup Language;

XML: Extensible Markup Language,

Everyone has puzzled place can refer to the following article.

Development trend:

HTML (Hyper-text Markup Language)--xhtml (Extensible Hypertext Markup Language)--xml (extensible Markup Language);

Html:

1. Not sensitive to case;

2. The label does not need to appear in pairs;

3.<br>;

Xhtml:

1. Sensitive to case, must be lowercase;

2. The label must appear in pairs, and there must be an end tag on the start tag;

3. Attribute value must be within quotation marks;

4. Attribute minimization is not supported:

Eg: correct: <input checked= ' checked ' >

Error: <input checked>

5.name attribute is not in favor of use, will be eliminated later;

6. Empty elements also want to end tags: such as:<br/>,
Xml:

HTML will eventually evolve to xml,xhtml is a transition from HTML to XML development, and XHTML features are also suitable for XML;