SGML
SGML, Short for standard generalised markup language, is a standard for organising and tagging document elements. It was developed in the 1980s, giving birth to markup languages such as HTML and XML. Rather than a language, SGML acts as a description of how to define document language. It follows a straightforward structure that both humans and machines can read. SGML is an ISO standard. It provides a robust framework for defining document structures and markup languages. SGML layouts define document structures and types through document type definitions. Similar to HTML and XML, SGML uses tags to denote elements in a document and to organise content. SGML allows data sharing and document processing when their structure and integrity are crucial. SGML is the foundational language of the modern web. It has significantly influenced markup languages and document processing standards.