In XML related technologies, what is XPath mainly used for?

Introduction / Context:
XML (Extensible Markup Language) is widely used for representing structured data. Many technologies exist around XML, including ways to query and transform XML documents. XPath is a foundational component in this ecosystem. This question checks whether you know the main purpose of XPath in relation to XML documents.

Given Data / Assumptions:

• We have XML documents that are tree structured, with elements, attributes, and text nodes.
• XPath is mentioned as a named technology.
• The options include tasks such as styling, querying, encryption, routing, and binary formatting.
• We assume basic awareness that XML is used for data rather than for low level networking or binary storage.

Concept / Approach:
XPath stands for XML Path Language. It is designed to navigate through elements and attributes in an XML document using path like expressions. XPath expressions can select nodes that match certain criteria, compute values, and serve as the basis for higher level technologies such as XSLT and XQuery. It does not define visual styles, perform encryption, manage routing, or format binary data.

Step-by-Step Solution:
Step 1: Recall that XML documents form a hierarchical tree, where each element can contain child elements, attributes, and text. Step 2: Understand that XPath provides a syntax similar to file system paths, such as /root/child/item, to navigate this tree. Step 3: Recognize that XPath expressions can filter nodes using predicates, functions, and conditions. Step 4: Compare this functionality with the options. Only option b describes a query language for navigating and selecting nodes in an XML document. Step 5: Confirm that tasks like styling and encryption are handled by other technologies, not by XPath itself.

Verification / Alternative check:
Consider an XML document representing a bookstore. You can write an XPath expression such as //book[price > 500] to select all book elements whose price element is greater than a certain value. This example clearly shows that XPath is a query and navigation language for XML node selection, supporting the explanation in option b.

Why Other Options Are Wrong:
To define visual style sheets for formatting HTML pages describes technologies such as CSS or XSLT when applied to XML, not XPath. To encrypt sensitive data within XML elements before transmission is the role of security mechanisms, not a navigation language. To manage network routing tables for web servers and to format binary files for storage on disk are completely unrelated to XML query languages.

Common Pitfalls:
Some learners confuse XPath and XSLT. XSLT is a transformation language that often uses XPath expressions inside it. Remember that XPath itself is about selecting and navigating nodes, while XSLT uses those selections to transform XML into other documents such as HTML or text.

Final Answer:
XPath is mainly used to provide a query language for navigating and selecting nodes in an XML document.