XSLT, which stands for Extensible Stylesheet Language Transformations is a programming language. XSLT is based on XML. It is part of XSL, and is used for transforming XML documents, most of the time. The language is Turing complete. This means that anything that can be computed by a Turing machine can also be done in XSLT.

Uses for XSLT include:

Presentation-oriented publishing (POP): A transformation is done for presentation purposes. Examples of such transformations include the generation of XHTML, SVG and Docbook.
Message-oriented Middleware (MOM): A transformation is done to make communication between two different systems possible. This allows to exchange data between both systems.