Which statement correctly describes XML?

The correct choice accurately identifies XML as a markup language used for structuring data. XML, which stands for eXtensible Markup Language, is designed to store and transport data while focusing on the structure and organization of that data rather than on its presentation. It uses tags to define elements and attributes, enabling a hierarchical representation of information.

This capability allows XML to organize data in a way that is both human-readable and machine-readable, making it an ideal format for data interchange between different systems and applications. For example, it is widely used in web services, configuration files, and various data storage scenarios.

In contrast, the other options do not correctly describe XML's purpose or functionality. It is not a programming language, which would involve writing code to implement algorithms and processes. It is also not a type of database, as databases are systems for storing and managing data rather than formats for data representation. Lastly, XML is not a data visualization tool; visualization tools typically focus on presenting data in graphical formats, while XML is concerned with the underlying data structure.