I have a lot of experience in using social networks. From MySpace's hey-day to Instagram's new popularity, I've always been curious enough to try out accounts on social websites to see what they're about.
Currently, Facebook is of course the big one. It's a good way for me to keep in touch with friends and family that don't live in the area. I've also found it a good way to get to know new co-workers more quickly. And yes, I use it to play little games and post in-jokes among my friends. Facebook's also a good way to keep up with my interests, whether it's yesterday's match results for Arsenal FC or sales at my favorite stores. Facebook also provides a cheap, easy way to show support. I can keep up with the latest news from the pet rescue where I adopted my puppy from (currently undergoing a suit against a land developer who is trying to push them out) or spread "word of mouth" about my friend's photography start-up.
I also have a Twitter account, although I will often forget about it. It's a great way to send out a quick thought or joke to a friend, but I prefer Facebook's more personal approach. Really, what Twitter is great for is news. I can follow the accounts of various organizations, or persons, and be kept up-to-date. Although my timeline gets so cluttered that many a time I don't feel like scrolling all the way through it. There is the lists feature that would allow me to categorize those I follow--athletes, game developers, book reviewers--but I have only a very little experience using it. At this point, I follow so many accounts it seems more hassle than its worth.
Tumblr is fun, and a great way to connect with people who have the same interests I do. Many people use it as a more personal platform, but I find it a way to relax and joke about pop culture. It's also used by many social interest/justice groups to promote awareness of their communities. More and more professional organizations are creating Tumblr accounts because of its flexibility as a micro-blog. As such, it's particularly good for photographers.
Instagram is a fun little account that I mainly keep to do quick touch-ups to photos on my phone. It also makes it incredibly to post an image to my Facebook, Twitter, and Tumblr all in one tap. I haven't fully embraced the social side of this social network, but I see my younger cousins using it like crazy. Several youth services forums that I read up on have pointed out that Instagram is the most popular social network for the young teen/young adult crowd and urge YA librarians to capitalize on that.
I also have a LinkedIn account. I unfortunately don't have too much experience with this network yet, but I see the potential it has in helping me build a professional network. I didn't have much working experience (at least worth bragging about online) until the last year and a half, but when I left my first "grown-up" job, it was great to see support roll in from co-workers and former clients on that platform. Many employers and organizations check on a potential employee's digital footprint nowadays, so it's nice to have these endorsements in an easy format through LinkedIn.