The Adobe InDesign Markup Language (IDML) is an XML-based file format introduced by Adobe Systems for its professional desktop publishing software, InDesign. Unlike the proprietary binary .indd format, IDML is a collection of XML files compressed into a single package, which makes it highly accessible for developers and third-party applications to programmatically generate, modify, or extract content from InDesign documents. It serves as a bridge for backward compatibility, allowing users to open newer InDesign files in older versions of the software. Because it is text-based, it is also frequently used in translation workflows, as translation management systems can easily parse the XML structure to translate text while preserving layout metadata. It is the industry standard for interchange between different versions of Adobe InDesign and serves as a robust archival format for print and digital publishing projects.