Markup Language:-
A markup language provides a way to combine a text and extra information about it. The extra information, including structure, layout, or other information, is expressed using markup, which is typically intermingled with the primary text. The best-known markup language in modern use is HTML (HyperText Markup Language), one of the foundations of the World Wide Web. Originally markup was used in the publishing industry in the communication of printed work between authors, editors, and printers.
The term markup is derived from the traditional publishing practice of "marking up" a manuscript, that is, adding symbolic printer's instructions in the margins of a paper manuscript. For centuries, this task was done by proofreaders who marked up text to indicate what typeface, style, and size should be applied to each part, and then handed off the manuscript to someone else for the tedious task of typesetting by hand. A familiar example of manual markup symbols still in use is proofreader's marks, which are a subset of larger vocabularies of handwritten markup symbols.

GenCode
The idea of markup languages was apparently first presented by publishing executive William W. Tunnicliffe at a conference in 1967, although he preferred to call it "generic coding." Tunnicliffe would later lead the development of a standard called GenCode for the publishing industry. Book designer Stanley Fish also published speculation along similar lines in the late 1960s. Brian Reid, in his 1980 dissertation at Carnegie Mellon University, developed the theory and a working implementation of descriptive markup in actual use. However, IBM researcher Charles Goldfarb is more commonly seen today as the "father" of markup languages, because of his work on IBM GML, and then as chair of the International Organization for Standardization committee that developed SGML, the first widely used descriptive markup system. Goldfarb hit upon the basic idea while working on an early project to help a newspaper computerize its work flow, although the published record does not clarify when. He later became familiar with the work of Tunnicliffe and Fish, and heard an early talk by Reid which further sparked his interest.

History
It must be noted that the details of the early history of descriptive markup languages are hotly debated. However, it is clear that the notion was independently discovered several times throughout the 70s (and possibly the late 60s), and became an important practice in the late 80s.