Term of the Moment
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Definition: XML
(EXtensible Markup Language) The most widely used semi-structured format for data. Introduced by the W3C in 1998, XML files contain tags and text similar to HTML. However, whereas HTML defines how elements display and print, XML assigns meaning to the elements. HTML uses predefined tags, and so does XML. However, most of the content in an XML file is defined by the developer. Thus, just like database records, virtually any data items, such as "product," "sales rep" and "amount due," can be specified.
XML Is Only a Format
When introduced, XML was hyped as the panacea for e-commerce, but it was only a first step. The human-readable XML tags provide a simple format, but the intelligent defining of these tags to serve business needs properly and everyone's compliance in using them determine XML's value. Countless vocabularies have been developed for vertical applications; so many in fact, that a universal language was developed to provide a standard for interoperability between them (see UBL). See XML vocabulary, Web services, SOA and EDI).
XML Documents Can Define Themselves
An XML document can include a self-describing set of rules that identify the tags and their relationships; for example, only one XYZ tag is allowed within an ABC tag, or there must be one XYZ tag within every ABC tag and so forth. See XML schema.
More Rigid than HTML
Unlike HTML, which uses a rather loose coding style and is more tolerant of coding errors, XML pages have to be "well formed" and comply with the rules. See XSLT, DTD, DOM, XHTML, JSON, HTML, SGML, SMIL and XML-RPC.
XML vs. HTML Tags
From Text to XML
XML Is Only a Format
When introduced, XML was hyped as the panacea for e-commerce, but it was only a first step. The human-readable XML tags provide a simple format, but the intelligent defining of these tags to serve business needs properly and everyone's compliance in using them determine XML's value. Countless vocabularies have been developed for vertical applications; so many in fact, that a universal language was developed to provide a standard for interoperability between them (see UBL). See XML vocabulary, Web services, SOA and EDI).
XML Documents Can Define Themselves
An XML document can include a self-describing set of rules that identify the tags and their relationships; for example, only one XYZ tag is allowed within an ABC tag, or there must be one XYZ tag within every ABC tag and so forth. See XML schema.
More Rigid than HTML
Unlike HTML, which uses a rather loose coding style and is more tolerant of coding errors, XML pages have to be "well formed" and comply with the rules. See XSLT, DTD, DOM, XHTML, JSON, HTML, SGML, SMIL and XML-RPC.
XML defines data, whereas HTML defines the page layout ("b" stands for boldface). All elements are wrapped within "start" and "end" tags, also called "open" and "close" tags. The start tags begin with a less-than character (<) and end with a greater-than character (>). All end tags begin with the less-than and slash (</).
To display this encyclopedia online, the source text files are converted to several XML-coded formats, and this example is one definition from one of the feeds. The "p" tags define a paragraph, and "strong" tags indicate boldface text so words can be emphasized in text-to-speech readers for the blind. The "for" is color coded because this text was rendered in a source code editor, and "for" is a common programming command. See source code.