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Today Xiaobian to share with you what are the differences between XML and HTML related knowledge points, detailed content, clear logic, I believe most people still know too much about this knowledge, so share this article for everyone to refer to, I hope you read this article after some gains, let's learn about it together.

1. XML Guide

XML is an information transfer tool independent of software and hardware. XML is a W3C recommendation. XML is ubiquitous, and it's amazing to see how quickly XML standards are being developed and how quickly software developers are adopting it.

XML currently plays as much a role in the Web as HTML, which has always been the cornerstone of the Web. XML is the most commonly used tool for transferring data between programs and is becoming increasingly popular in the field of information storage and description.

II. Basic overview of XML

XML(Extensible Markup Language), a subset of the Standard Universal Markup Language, is a markup language used to mark electronic documents to make them structured. In electronic computers, marks refer to information symbols that can be understood by computers. Through such marks, computers can process various information such as articles.

It can be used to label data, define data types, and is a source language that allows users to define their own markup language. It is well suited for World Wide Web delivery and provides a uniform way to describe and exchange structured data independent of the application or vendor. It is a cross-platform, content-dependent technology in the Internet environment and an effective tool for dealing with distributed structured information today. Back in 1998, the W3C released the XML 1.0 specification, which was used to simplify document information transfer over the Internet.

Q. What is XML?

XML stands for Extensible Markup Language.

XML is a markup language, much like HTML (Hypertext Markup Language).

XML is designed to transmit data, not display it.

XML tags are not predefined, you need to define your own tags

XML is designed to be self-descriptive

XML is a W3C Recommendation

Main differences between XML and HTML

XML and HTML are designed for different purposes.

XML is designed to transport and store data, with the focus on the content of the data

HTML is designed to display data with focus on how the data looks

HTML is designed to display information, while XML is designed to transmit information.

XML is not a substitute for HTML, XML is a complement to HTML.

It is important to understand that XML does not replace HTML. In most Web applications, XML is used to transmit data, while HTML is used to format and display data

Why XML is needed

Solve the problem of irregular data transmission

can describe tree structures very well.

Can be used as a profile

VI. XML without any action

XML is nonexistent. It may be a bit hard to understand, but XML doesn't do anything. XML is designed to structure, store, and transmit information.

Let's illustrate this with a simple example written in a notepad.

Here is a list of books, stored as XML:

XML Usage

39.00

Java is fully utilized.

139.00

Oracle uses the entire

59.00

The note above is self-descriptive. It has a header and a message, and includes information about both the sender and the recipient. However, the XML document still doesn't do anything. It is simply information wrapped in XML tags. We need to write software or programs to send, receive, and display this document.

XML is just plain text.

XML is nothing special. It's just plain text. Any software capable of processing plain text can process XML. However, XML-reading applications can target XML tags. The functional meaning of the tag depends on the nature of the utilization program. We'll see what XML tags can do in the future.

With XML you can invent your own tags

The tags in the example above are not defined in any XML standard (e.g. and etc.). These tags were invented by the author of the document. This is because XML has no predefined tags. XML allows authors to define their own tags and their own document structure.

The tags used in HTML (and the structure of HTML) are predefined. HTML documents use only tags defined in the HTML standard (such as

and so on.)

IX. XML tree structure

As we can see in the book example above, XML documents form a tree structure that starts at the root and expands to the branches.

An XML document instance

XML uses a simple, self-descriptive syntax:

George

John

Reminder

Don't forget the meeting!

The first line is the XML declaration. It defines the version of XML (1.0) and the encoding used (UTF-8, GBK, etc.);

The next line describes the root element of the document (like saying,"This document is a note"):

The next four lines describe the root's four child elements (to, from, heading, and body):

George

John

Reminder

Don't forget the meeting!;

The last line defines the end of the root element: .

From this example, assume that the XML document includes a note from John to George.

XML has excellent self-descriptive properties, don't you agree?

XML documents constitute a tree structure

XML documents must include a root element. This element is the parent of all other elements.

The elements in an XML document form a document tree. The tree starts at the root and expands to the bottom of the tree.

All elements can have children:

.....

The terms parent, child, and sibling are used to describe relationships between elements. Parent elements have child elements. Children at the same level become siblings (brothers or sisters). All elements can have text content and attributes (similar to HTML).

Represents a book in XML that:

Everyday Italian

Giada De Laurentiis

2005

30.00

Harry Potter

J K. Rowling

2005

29.99

Learning XML

Erik T. Ray

2003

39.95

The root element in the example is. All elements in the document are included in. The element has four child elements:

、

、、。

X. XML usefulness

XML is often used to simplify data storage and sharing

XML separates data from HTML

If you need to display dynamic data in an HTML document, it will take a lot of time to edit HTML every time the data changes. With XML, data can be stored in separate XML files. This way you can focus on using HTML for layout and display and ensure that modifying the underlying data no longer requires any changes to HTML. By using a few lines of JavaScript, you can read an external XML file and update the data content in HTML.

(2) XML Simplified Data Sharing

In the real world, computer systems and data store data in incompatible formats. XML data is stored in plain text format, thus providing a software-and hardware-independent method of data storage. This makes it easier to create data that can be shared by different applications.

(3) XML simplifies data transmission

XML makes it easy to exchange data between incompatible systems. One of the most time-consuming challenges for developers has been exchanging data between incompatible systems on the Internet. Exchanging data in XML reduces this complexity because it can be read by a variety of incompatible utilities.

(4) Changes to XML Simplification Platform

Upgrading to a new system (hardware or software platform) is always time-consuming. Large amounts of data must be converted, and incompatible data is often lost. XML data is stored in text format. This makes it easier to extend or upgrade XML to new operating systems, new utilities, or new browsers without losing data.

XML makes your data more useful

Because XML is independent of hardware, software, and utilities, XML makes your data more usable and useful. Different utilities can access your data, not only in HTML pages, but also from XML data sources. Through XML, your data can be used by a variety of browsing devices (handheld computers, voice equipment, news browsers, etc.), as well as by blind or otherwise disabled people.

XML is used to create new Internet languages

Many new Internet languages are created using XML, examples include:

XHTML -Latest HTML version

WSDL -used to describe available web services

WAP and WML -markup languages for handheld devices

RSS -Language for RSS feeds

RDF and OWL -used to describe resources and ontologies

SMIL -for describing web-oriented multimedia

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