Learning about XML (1)

Overview of XML

1. What is XML?

XML refers to an extensible markup language.

2. What is the difference between XML and HTML?

• HTML tags cannot be customized, XML tags can only be customized;
• The xml syntax requirements are not strict, but the xml syntax requirements are extremely strict and must be paired tags.

• XML and HTML are designed for different purposes:

  XML was designed to transmit and store data, with the focus being on the content of the data.HTML is designed to display data, and the focus is on the appearance of the data.

XML syntax rules

1.XML must contain the root element, which is the parent of all other elements.

2.XML header declaration: not mandatory, optional.

3. All XML elements must have a closing tag

 hello world /***errorhello world //correct

4.XML tags are case sensitive

5.XML must be properly nested

6. The XML attribute value must be enclosed in quotation marks, both single and double quotation marks are acceptable.

7. Entity reference

In XML, some characters have special meanings.

If you put the character "<" inside an XML element, an error occurs because the parser treats it as the start of a new element.

This will generate an XML error.

Writing at the end, the article may have some mistakes, please criticize and point out any shortcomings.