XSLT, or Extensible Stylesheet Language Transformations, is a language used for transforming and rendering XML documents. It allows developers to convert XML data into different formats, such as HTML, text, or other XML structures, making it easier to present and manipulate data. Using XSLT, you can define rules for how to extract and format data from an XML file. This is particularly useful for web applications and data interchange, as it enables the separation of data from its presentation, allowing for more flexible and maintainable code.