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Differentiate between XML and XSL. 

Difference Between XML and XSL (XSLT) – Easy Explanation

In web technologies, XML and XSL/XSLT are used together but serve different purposes. XML stores data in a structured, self-descriptive way, while XSL/XSLT defines how to transform or present that data (for example, converting XML into HTML for display).

What is XML?

  • XML (eXtensible Markup Language) is used to represent and transport data.
  • It focuses on the structure and meaning (content), not on how it looks.
  • It uses custom tags designed by the author to describe the data.
  • Commonly saved with the .xml extension.

What is XSL/XSLT?

  • XSL (eXtensible Stylesheet Language) is a family of technologies for XML presentation and transformation. The most used part is XSLT (XSL Transformations).
  • XSLT describes rules (templates) to transform XML into other formats like HTML, text, or another XML.
  • It uses XPath expressions to select parts of the XML.
  • Commonly saved with the .xsl or .xslt extension.

Key Differences Between XML and XSL

  1. Purpose: XML stores data; XSLT transforms and presents that data.
  2. Content vs. Rules: XML contains actual information; XSLT contains transformation rules and templates.
  3. Syntax: XML uses user-defined tags; XSLT uses special tags with the xsl: prefix (e.g., xsl:template, xsl:value-of).
  4. Processing: XML is parsed by XML parsers; XSLT is executed by an XSLT processor to produce output.
  5. Output: XML by itself does not produce a view; XSLT produces new documents (HTML, XML, or plain text).
  6. Validation: XML can be validated with DTD/XSD; XSLT is validated against XSLT rules and uses XPath for selection.
  7. Reuse: The same XML can be styled many ways using different XSLT stylesheets; one XSLT can transform many XML files of similar structure.
  8. Use Case: XML is for data exchange and storage; XSLT is for data transformation, presentation, filtering, and sorting.

How XML and XSLT Work Together

Think of XML as raw data and XSLT as the recipe that turns it into a web page or report. An XSLT processor reads both and generates the final output.

XML data + XSLT stylesheet --(XSLT processor)--> HTML (or XML/text)

Example: XML and XSLT in Text Format

The following is your sample XML and XSLT shown as plain text (safe to copy and view):

<book>
  <title>Web Tech Basics</title>
  <author>Riya Sharma</author>
</book>

<!-- Sample XSLT (XSL) that transforms the XML to HTML) -->
<xsl:stylesheet version="1.0" xmlns:xsl="http://www.w3.org/1999/XSL/Transform">
  <xsl:template match="/book">
        <h1><xsl:value-of select="title"></xsl:value-of><br></h1>
        <p>Author: <xsl:value-of select="author"></xsl:value-of></p>
  </xsl:template>
</xsl:stylesheet>

Expected Output (Text Format)

When the XSLT runs on the above XML, the generated HTML would look like:

<h1>Web Tech Basics<br></h1>
<p>Author: Riya Sharma</p>

Summary: XML defines the data; XSL/XSLT defines how to transform and present that data. Together, they help convert raw information into readable web pages or reports.