Depends on how you define the term. Historically, the term came up in the verge of Web 2.0 and was distinct from other social online media in that a specific s

Depends on how you define the term. Historically, the term came up in the verge of Web 2.0 and was distinct from other social online media in that a specific software was the basis for each respective SN. So for example Twitter is SN because you had the app on the phone that was only Twitter so that was SN. But an online forum was not, because everybody could obtain the same software and run a forum. So by that defition HN is social media.