XML (eXtensible Markup Language) is a flexible, text-based format used for structuring, storing, and exchanging data between systems, especially over the internet. Unlike traditional markup languages such as HTML, which are used to display data, XML is designed to describe data in a structured manner, making it easier to transport and interpret across diverse systems. At its core, XML is a way to represent information in a hierarchical structure of elements, attributes, and data. The data in XML is enclosed within user-defined tags, which allows the structure to be both human-readable and machine-readable. The tags provide metadata about the data, giving context and meaning to the content they enclose. One of the fundamental features of XML is that it is extensible, meaning that users can define their own tags according to the needs of the data being represented. An XML document starts with a declaration line, often defining the version of XML being used and the character encoding. For example: ```xml ``` Following this declaration, the document consists of elements enclosed in angle brackets, where each element has an opening tag, content, and a closing tag. Elements can be nested within each other, allowing the creation of a tree-like structure. For example, consider the following XML snippet: ```xml John Doe 2025 ``` In this example, the `` element is the root element, containing child elements such as `