Before processing can begin, the part of the XML document with the information to be copied to the output must be selected with an XPath expression. The selected section of the document is called a node and is normally selected with the match operator.

In the above statements, the <xsl:template> element defines a template. The match=”/” attribute associates the template with the root node of the XML source document. Another approach is to match the document element (the element that includes the entire document).

The <xsl:apply-templates> Element
The <xsl:apply-templates> element applies a template to the current element or to the current element’s child nodes. If we add a select attribute to the <xsl:applytemplates> element it will process only the child element that matches the value of the attribute. We can use the select attribute to specify the order in which the child nodes are processed.

The <xsl:value-of> Element
The <xsl:value-of> element can be used to extract the value of an XML element and add it to the output stream of the transformation. For example, the given expression will select the value of Emp_Id attribute of the specified
element and write to the output:

Note: The value of the select attribute is an XPath expression. An XPath expression works like navigating a file system; where a forward slash (/) selects subdirectories.

The <xsl:for-each select=”elementName “> Element
The ‘for-each’ expression is a loop that processes the same instructions for these elements. The XSL <xsl:for-each> element can be used to select every XML element of a specified node-set. For example, the given expression finds all ‘Employee’ elements in the ‘Employee-Detail’ element context using the XPath expression ‘Employee-Detail/ Employee’.

If the selected node contains all elements in the root, all of the ‘Employee-Detail’ elements will be selected.

Introduction to XSLT
Extensible Stylesheet Language Transformations (XSLT) is an XML-based language that transforms an XML documents and generates output into a different format
such as HTML, XML or another type of document that is recognized by a browser like WML, and XHTML.

XSLT is an extension of XSL, which is a stylesheet definition language for XML With XSLT you can add/remove elements and attributes to or from the output file. You can also rearrange and sort elements, and make
decisions about which elements to hide and display.

XSLT uses XPath to find information in an XML document. XPath is used to navigate through elements and attributes in XML documents.