XML

A markup language designed by the W3C for encoding structured data in a format that is both human-readable and machine-readable. Unlike HTML, which has a fixed set of tags focused on presentation, XML allows authors to define custom tags that describe the meaning and structure of data. In accessibility, XML is significant because it enables the separation of content from presentation — data marked up in XML can be transformed into multiple accessible formats (HTML, Braille, speech) using stylesheets like XSLT. XML also underlies many accessibility-related standards and formats, including EPUB for accessible digital publishing, MathML for mathematical notation, and SVG for scalable vector graphics.