OK gonna expand my answer a bit, because I was tired and just saying "social-media" is a lame way to express it...
Facebook: used to be the cool thing, but not anymore too many moms/angry repubs grandpas/"funny" moms and fucking minions...yeah you can trim your friends list etc etc, but kids don't have time for that. so the Younger set moved to Instagram, post a pic keep it simple, I kinda get that.
kik/line/whatsapp/line and any other messaging service, there just seems to be so many, I get why some international folks use them due to restrictions/lack of service and whatnot, just seem like there is a ton, and you'd think one or two would be the universal choice by now. I do know 4chan uses kik for questionable stuff other than that I've know fuck all bout the rest save for whatasapp because it get's talked about a fair amount.
Snapchat: hot for nudes you don't want people saving, except I think people can still save them?
Tumblr: awesome for porn, kinda pointless for anything else.
Selfie culture: I am not self absorbed so I am not into it, fixing a friends laptop and seeing 100000000000000 pics of his daughter in the same duckface induced pose, idk kids these days, lol
Let's plays/twitch/JSE/Markplier/PewDiePie: Play the fucking game yourself, ugh. I wish I knew spazzy morons would be hot, I can fake that all day long. I can't totally complain as I do enjoy shit like Game Sack, Classic Game room, Classic Gaming Quarterly and the like, maybe it's just the same shit but for old fart like me.
So it's not to say I don't understand it all, I just don't see a need for it all, but if it works for some hell why not.
The one thing I will admit to liking kinda is GMM, except Link, fuck Link...