SGML, or Standard Generalized Markup Language, is a system for organizing and tagging elements within a document. It allows for the creation of structured documents that can be easily shared and understood across different systems and platforms. SGML serves as a foundation for other markup languages, including HTML and XML, enabling the representation of complex data in a standardized format. By using SGML, organizations can ensure consistency in document formatting and facilitate data interchange. This makes it particularly useful in fields such as publishing, where documents need to be produced in various formats while maintaining their integrity and structure.