Is an Extensible Mark-up Language simple but strict, which plays a key role in the exchange of a wide variety of data. Is a language similar to HTML, but its main function is to describe data and not display them as is the case with HTML. XML is a format that allows the reading of data across different applications. XML technologies are a set of modules that offer useful services to the most frequently by users. XML is used to structure, store and share information.

XML is designed to make things simpler for the automated programs that need to interpret the document. After be designed and put into production, it is possible to extend XML with the addition of new tags, so you can continue to use without any complication. The analyzer is a standard component, it is not necessary to create a parser for each language version of XML. This will prevent bugs and accelerates application development. If third parties choose to use a document created in XML, it is easy to understand its structure and processes. Improved compatibility between applications.

The development of XML started 1996 and has been a W3C recommendation since February of 1998. XML was developed in the early'80s, ISO Standard since 1986, and widely used for large documentation projects. The development of HTML began in 1990. The designers of XML took the best parts of SGML, guided by experience with HTML, and produced something that is no less powerful than SGML, and more widely regular and easy to use.

There are two current versions of XML. The first, XML 1.0, was initially defined in 1998. It has undergone minor revisions since then, without being given a new version number, and is currently in its fifth edition, as published on November 26, 2008. It is widely implemented and still recommended for general use. The second, XML 1.1, was initially published on February 4, 2004, the same day as XML 1.0 Third Edition, and is currently in its second edition, as published on August 16, 2006. It contains features, some contentious, that are intended to make XML easier to use in certain cases mainly enabling the use of line-ending characters used on EBCDIC platforms, and the use of scripts and characters absent from Unicode 2.0. XML 1.1 is not very widely implemented and is recommended for use only by those who need its unique features.

Among the available XML technologies are:

Extensible Language Style Sheets, whose main objective is to show how the content should be structured, how the content should be designed and how the home should be paginated in a presentation such as a window in a Web browser or a mobile device, or set of pages from a catalog, report or book.

Language of Routes XML is a language for accessing parts of an XML document.

XML Link Language is a language that allows you to insert elements into XML documents to create links between XML resources.

Addressing Language XML is a language that allows access to the internal structure of an XML document, ie its elements, attributes and content.

XML Query Language, a language that facilitates data extraction from XML documents. Offers the possibility of flexible queries to extract data from XML documents on the Web.

XML 1.0 is a specification that defines what the “tags” and “attributes”. Beyond XML 1.0 is a growing set of modules that offer useful for important tasks often demanded. XSL functions as a language for creating advanced stylesheets. It can transform, filter and sort XML data and format them basing on their values. XPath identifies parts of a particular XML document, such as its attributes, elements, etc. XLink in turn, describes a standard way to add hyperlinks to an XML file. A mechanism for linking to other XML documents. Works similar to a link on a Web page, ie it works as you would <a href=“”>, only one link to href is unidirectional. However, XLink allows you to create bidirectional links, which implies the possibility of moving in two directions. This facilitates the obtaining of information remotely as resources rather than simply as Web pages. XPointer syntax works as a pointing to certain parts of an XML document is an extension of XPath. It is used to reach certain parts of an XML document. First, it allows XLink provides the link to the XML and then use XPointer to go to a specific point in the document. Its operation is similar to the identifiers of fragments in a HTML document as it is added to the end of a URI, then it does is find the location specified in the XML document. As an extension of XPath XPointer, XPointer has all the advantages of XPath and also provides a range in an XML document, ie XPointer is a possible end point and a starting point, which includes all the XML elements within these two points. Finally, XQL, query language, is based on operators seeking a data model for XML documents that can perform queries in a multitude of document types such as structured documents, document collections, databases, DOM structures, catalogs, etc.

XML technology aims to solve the problem of expressing structured information in the most abstract and reusable as possible. That information is structured means that consists of well defined parts, and that those parts are composed in turn of other parties. Like HTML, XML uses tags (words enclosed by '<' and '>') and attributes (of the form name = “value”). While HTML specifies what each tag and attribute means and often appear in a browser how the text between them, XML uses tags only to delimit pieces of data, and leaves the interpretation of the data completely to the application that reads. “ Thus, with the emergence of ”

“In an XML file, you should not assume that is a paragraph, depending on the context, it may be a page or a place.

-<?xml version=“1.0” encoding=“ISO-8859-1”?> -<libro> - <titulo></titulo> - <capitulo> - <titulo></titulo> - <seccion> - <titulo></titulo> - </seccion> - </capitulo> -</libro> Félix Miranda Visiedo