An international standard system used for organizing and tagging elements of a document.
It does not do any particular formatting but instead tags elements that can then be used to format elements in different ways.
A standardized language (ISO 8879) used to depict structured texts.
SGML is very versatile, but is difficult to use due to its size.
Of greater significance is XML, a reduced version of SGML designed specifically for exchanging structured data in the Internet.