The origin of the social web is various, but the origin of the *term* is attributed to Howard Rheingold.
The term “social Web” was coined by Howard Rheingold for this network in 1996; Rheingold was quoted in an article for Time on his website “Electric Minds”, described as a “virtual community center” that listed online communities for users interested in socializing through the Web, saying that “The idea is that we will lead the transformation of the Web into a social Web”. (wikipedia)
It’s worth noting that the use of forms (crucial in wiki as well) was key here. Forms became the way to hack a read/write web together.
The HTML form was born in the curses browser. See Birth of the Form.