HTML is an application of the Standard Generalized Markup Language (SGML) which is the International Standard (ISO 8879) for text markup. The principle is that text markup concentrates on structure rather than appearance, making the files more reuseable and leaving the visual details to the end-user software (like the browser you're reading this with now).

HTML is an application of ISO Standard 8879:1986 Information Processing Text and Office Systems; Standard Generalized Markup Language (SGML). The HTML Document Type Definition (DTD) is a formal definition of the HTML syntax in terms of SGML.


Standard Generalized Markup Language (SGML) is an international standard (ISO 8879) used for document representation and electronic interchange. It is being used by an ever-increasing number of organizations to facilitate the creation, management, storage and delivery of document-based information. As a standard, SGML goes far beyond the goal of information interchange; it is also a tool for managing and protecting an organizations data assets.

History of SGML

Why SGML was created

  • Standard Generalized Markup Language is a data encoding that allows the information in documents to be shared -- either by other document publishing systems or by applications for electronic delivery, configuration management, database management, inventory control, etc.
  • Because it provides a vendor-neutral, formal, international standard for information interchange, SGML is being widely adopted for sharing document-based information in open systems environments.

Benefits of SGML and open systems

There are three key benefits of the open systems approach that employs SGML:

Structure of SGML