The difference between HTML and XHTML

1. All marks must have a corresponding closing tag

2. All tag elements and attributes must have a lowercase name

3. All XML tags must be properly nested

4. All attributes must be enclosed in quotation marks "".

5, all the < and & special symbols in the code representation

6. Assign a value to all attributes

7. Do not use "--" in the annotation content

8, the picture must have the explanatory text

The difference between HTML and XHTML