XML, or eXtensible Markup Language, is a versatile markup language designed for storing and transporting data in a structured format. Unlike HTML, which is used for displaying data, XML focuses on the representation of data and its semantics. It enables users to define their own tags and data structures, making it adaptable to various applications. In the context of AI and machine learning, XML is often used to interchange data between systems, configure models, and represent hierarchical data structures. Its human-readable nature facilitates debugging and ensures compatibility across different platforms and programming languages.