XML, which stands for eXtensible Markup Language, is a markup language designed for storing and transporting data. It is both human-readable and machine-readable and is widely used for data representation and interchange on the web and in various software applications.

Key Features of XML:

1. Structured Data: XML allows you to create a structured format for data, which is composed of elements (tags) that can have attributes. This structure makes it easy to define the hierarchy and relationships between different pieces of data.

2. Self-Descriptive: XML files are self-descriptive in that they contain both data and the tags that define the data's structure. This makes it easier for computers and humans to understand the data without needing additional documentation.

3. Extensible: Users can create their own tags suited to their particular needs. This extensibility makes XML highly versatile and adaptable to many different applications.

4. Platform-Independent: XML is platform-independent, meaning that it can be used across different systems and technologies without compatibility issues. Data stored in XML can be easily shared between different systems.

5. Text-Based Format: Being a text-based format, XML is relatively easy to read and write. This allows for easier debugging and manual editing compared to binary formats.

6. Widely Supported: XML is supported by many programming languages and tools, making it easy to parse and manipulate XML data. Libraries and frameworks are available for handling XML in languages like Python, Java, C#, and many others.

Common Use Cases:

• Data Exchange: XML is often used for exchanging data between different systems, such as between a web service and a client application.
• Configuration Files: Many applications use XML to store configuration settings because it is easy to read and modify.
• Web Services: Technologies like SOAP (Simple Object Access Protocol) and RESTful APIs use XML to format the data in requests and responses.
• Document Formats: XML can be used as a basis for document formats such as SVG (Scalable Vector Graphics) and XHTML (a strict variant of HTML).

Example of XML Structure:

<bookstore>
    <book>
        <title lang="en">Example Book Title</title>
        <author>John Doe</author>
        <year>2023</year>
        <price>29.99</price>
    </book>
    <book>
        <title lang="fr">Titre de livre exemple</title>
        <author>Jane Doe</author>
        <year>2023</year>
        <price>39.99</price>
    </book>
</bookstore>

In this example, <bookstore> is the root element, and it contains multiple <book> elements, each with child elements like <title>, <author>, <year>, and <price>.

In summary, XML is a flexible and widely-used format for data serialization that facilitates data sharing and communication across diverse systems and applications.