SGML was created by Charles Goldfarb, Ed Mosher, and Raymond Lorie in the 1980s. The first SGML parser was written by Yuri Rubinsky in 1983.
HTML was originally developed as an application inside SGML, but the first official version was HTML 2.0
SGML and HTML are separate languages. HTML was originally based off some of SGML, with some significant simplifications. Since then, HTML has grown separately from SGML. Neither language is contained within the other.
That would be Tim Berners-Lee and Dan Connolly, if you are looking for the writers of the first IETF draft HTML spec. Though Tim was strongly influenced by, and considered HTML to be an application of SGML, SGML in itself was a descendant of GML from IBM and that was originally developed by 3 people, Charles Goldfarb, Edward Mosher, and Raymond Lorie in the 1960s.
Standard Generalized Markup Language is the full from of SGML.
XML was based off of the Standard Generalized Markup Language. It was built to fill the need for a strategic storage system that was easy to read and manipulate data with. XML was first developed to make SGML usable for Web purposes. SGML is a very large and complicated norm (thousands of pages). XML is kind of a subset of SGML, but at the same time has more restrictive rules, so that parsers and transformers working on XML are faster and more easy to implement.
SGML, or Standard Generalized Markup Language, is a type of metalanguage used for document elements. It is used for defining and tagging metalanguages used in specific documents.
standard generalized markup languge
SGML had a variety of rules that made it difficult to parse correctly, and less legible than XML. XML was made to be more machine and human friendly. Both languages are otherwise remarkably similar, including DTDs and validation, as one would expect, since SGML was the ancestor of XML.
Gilbert S. K. Wu has written: 'SGML theory and practice' -- subject(s): Electronic publishing, SGML (Document markup language)
Eve Maler has written: 'Developing SGML DTDs' -- subject(s): Electronic publishing, SGML (Document markup language), Hypertext systems, DTDs, DTD project management
Yes web pages are written in 'html' (Hyper Text Mark-up Language), which is an implemented subset of 'sgml' (The Standard Generalized Markup Language (ISO 8879:1986 SGML).