Introducing XPath and CSS selectors to process markup documents

In the Understanding the latest web technologies and Data-finding techniques used in web pages sections in Chapter 1, we explored and discussed HTML and XML markup documents and their availability across the web.

Normally, markup is a kind of labeling or tagging of parts, sections, or any entities in documents, which helps to identify the content and even process it using a third-party application. We call them tags in HTML (https://www.w3.org/html/) and nodes in XML (https://www.w3.org/standards/xml/). Hence, markup documents are a tree-like structure, containing tags or nodes (nested or individual), also known as an element tree.

Important note

XML documents have been pretty popular and common across the web since the start of the growing internet era. Readability, encoding support, interoperability, and data exchangeability are a few core powers of XML. XML is still supported by the latest web technologies...