Discussion boards also provide much longer-lasting content. Twitter and Facebook are totally ephemeral. Reddit content seems to be somewhat valid even after th

Discussion boards also provide much longer-lasting content. Twitter and Facebook are totally ephemeral. Reddit content seems to be somewhat valid even after the discussion has ceased, but once discussion leaves a subreddit front page it basically dies. That applies to HN too, of course. Discussion boards usually resurface a topic when someone answers, resulting in a longer discussion and a chance to revisit the topic.