1e41f4b71Sopenharmony_ci# XML Overview 2e41f4b71Sopenharmony_ci 3e41f4b71Sopenharmony_ci 4e41f4b71Sopenharmony_ciExtensible Markup Language (XML) is a markup language used to describe data. It aims to provide a common way to transmit and store data, especially data frequently used in web applications. XML does not predefine tags. As such, it is more flexible and widely used. 5e41f4b71Sopenharmony_ci 6e41f4b71Sopenharmony_ci 7e41f4b71Sopenharmony_ciAn XML file consists of elements, attributes, and content. 8e41f4b71Sopenharmony_ci 9e41f4b71Sopenharmony_ci 10e41f4b71Sopenharmony_ci- An element refers to a tag pair that contains text, attributes, or other elements. 11e41f4b71Sopenharmony_ci 12e41f4b71Sopenharmony_ci- Attributes provide additional information about an element. 13e41f4b71Sopenharmony_ci 14e41f4b71Sopenharmony_ci- Content is the data or sub-element contained in an element. 15e41f4b71Sopenharmony_ci 16e41f4b71Sopenharmony_ci 17e41f4b71Sopenharmony_ciXML supports the use of XML Schema Definition (XSD) or Document Type Definition (DTD) for defining the document structure. This allows you to customize rules to verify whether an XML document is in the expected format. 18e41f4b71Sopenharmony_ci 19e41f4b71Sopenharmony_ci 20e41f4b71Sopenharmony_ciXML also supports features such as namespaces, entity references, comments, and processing instructions, making it easy to adapt to diverse data requirements. 21e41f4b71Sopenharmony_ci 22e41f4b71Sopenharmony_ci 23e41f4b71Sopenharmony_ciThe common library provides XML-related basic capabilities, including [XML generation](xml-generation.md), [XML parsing](xml-parsing.md), and [XML conversion](xml-conversion.md). 24