What is XML and what is its function?

XML(eXtensible Markup Language) is an extensible markup language. Like HTML, it is SGML, a standard universal language. Xml is a cross-platform and content-related technology under the Internet environment, and it is a powerful tool for processing structured document information at present. XML is a simple data storage language, which uses a series of simple tags to describe data, and these tags can be established in a convenient way. Although XML takes up more space than binary data, it is very simple and easy to master and use.

XML is different from databases such as Access, Oracle and SQL Server. Database provides more powerful data storage and analysis capabilities, such as data indexing, sorting, searching, association consistency and so on. XML only displays data. In fact, the biggest difference between XML and other data representations is that it is extremely simple This may seem like a trivial advantage, but it is this that makes XML unique.

The simplicity of XML makes it easy to read and write data in any application, which soon makes XML the only universal language for data exchange. Although different applications also support other data exchange formats, in the near future, they will all support XML, which means that programs can be more easily combined with information generated under Windows, Mac OS, Linux and other platforms, and then XML data can be easily loaded into programs and analyzed, and the results can be output in XML format.

The predecessor of XML is SGML (Standard generalized markup language), which is GML (generalized markup language) developed by IBM since 1960s.

Like HTML, XML (Extensible Markup Language) is a subset of generalized markup language Standard (SGML), and generalized markup language Standard is a standard to describe the content and structure of data on the Internet. However, unlike HTML, HTML only provides a general method to display information on the page (without context-sensitive and dynamic functions), while XML provides context-sensitive functions for data, which inherits most functions of SGML, but uses less complicated technologies. .

In order to make SGML user-friendly, XML redefines some internal values and parameters of SGML, and removes many rarely used functions. These complex functions make SGML complicated when designing websites. XML retains the structural function of SGML, which enables website designers to define their own document types. At the same time, XML also introduces a new document type, so that developers don't have to define document types.

Because XML is formulated by W3C, the standardization of XML is the responsibility of W3C's XML working group, which is composed of experts from various places and industries. They exchanged their views on XML standards by email and put forward their own opinions (www.w3.org/TR/WD-xml). Because XML is a public format (not owned by any company), you don't have to worry that XML technology will become a profit tool for a few companies. XML is not a language that is attached to a specific browser.

XML (Extensible Markup Language) originated from an ancient language called SGML (Standard generalized markup language). The main purpose of SGML is to define the syntax of a markup language that uses tags to represent data.

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