XSLT (Extensible Stylesheet Language Transformations) is a language for transforming XML documents into other XML documents, HTML, or other formats. It is a key part of XSL (Extensible Stylesheet Language), a family of XML-based languages used for transforming and formatting XML data. XSLT stylesheets define rules for transforming XML elements and attributes into different structures or formats. The transformation process involves matching patterns in the input XML document and applying corresponding transformation rules defined in the XSLT stylesheet. XSLT is widely used in web development, data integration, and document processing to convert XML data into human-readable formats or to adapt XML data for different applications. It provides powerful features for manipulating XML data, including filtering, sorting, and aggregating data. XSLT processors are available in various programming languages and platforms, allowing developers to easily integrate XSLT transformations into their applications.