The main purpose of XML is serialization, i.e. storing, transmitting, and reconstructing arbitrary data. For two systems to exchange information, they need to agree upon a data format. XML supports this process,

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The material in this section is based on the XML Specification. This is not an exhaustive list of all the constructs that appear in XML; it provides an introduction to the key constructs most often encountered in day-to-day use.
Character An XML

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XML documents consist entirely of characters from the Unicode repertoire. Except for a small number of specifically excluded

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The XML specification defines an XML document as a well-formedtext, meaning that it satisfies a list of syntax rules provided in the specification. Some key points in the fairly lengthy

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A cluster of specifications closely related to XML have been developed, starting soon after the initial publication of XML 1.0. It is frequently the case that the term "XML" is used to refer to

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The design goals of XML include, "It shall be easy to write programs which process XML documents." Despite this, the XML specification contains almost no information about how programmers might go about doing such processing. The XML Infoset

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In addition to being well-formed, an XML document may be valid. This means that it contains a reference to a Document Type Definition (DTD), and that its elements and attributes are declared in that DTD and follow the grammatical rules for them that the DTD specifies.

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