How I learned of the existence of Pinterest:
Me: "Where did you say you posted that thing?"
Wife (annoyed): "Pinterest"
"Your what?"
"Pinterest"
"WTF is Pinterest?"
"Seriously?!"
edit: Pintrest, Pinterest, eh?
How I learned of the existence of Pinterest:
Me: "Where did you say you posted that thing?"
Wife (annoyed): "Pinterest"
"Your what?"
"Pinterest"
"WTF is Pinterest?"
"Seriously?!"
edit: Pintrest, Pinterest, eh?
Pinterest is aimed almost exclusively at women. You haven't heard of it because you're a dude and it's not marketed to you or your friends.
Hell, I'm enough of a tomboy that I don't really use it. I looked at it a year and a half ago when I first started transitioning to female because I heard that girls are supposed to like it, and I never got into it because it was all about fashion and shit that I have no interest in.
(OK, I did start getting into it in the last week or so... but I've mostly kept to the '80s/'90s nostalgia boards, which seems to be a much smaller part of the community than the fashion boards.)
The obvious use case is wedding planning. One board each for dresses, rings, locations, cakes, table decorations, invites, etc etc. or for redecorating a room - it's brilliant for that kind of stuff.
(I say brilliant, and I'm a Pinterest fan but the site has some user-hostile behaviours on mobile so I ise it a lot less often than I used to.
You're using one right now.
From Wikipedia
"Social media are computer-mediated tools that allow people to create, share or exchange information, ideas, and pictures/videos in virtual communities and networks." (Someone added "Web 2.0" later there but it's immaterial. Well, HN lets you vote without refreshing the page, I guess that's "Web 2.0")
The content is driven by users, either by creating (FB, Twitter) and/or curating it (Pinterest AND HN) -> Social Media
HN is actually a fairly primitive BBS running over TCP/IP.
(I'd say HN is not one, since we don't use a terminal program to access it and not using a modem over POTS)
One is centered around the topic, the other is centered around the person.
Pinterest is about curation of content and it is social media as well
Pinterest has a very different demographic which is more likely why GGP hadn't heard of it, but I would put it in the same bucket as Reddit/HN. Facebook, Twitter etc however are person-oriented.
The only thing all these have in common is user-generated content. But at that point you can call anything with user-generated content social media. Forums? Sure. Newspapers with curated user-submitted articles? Why not.