Tumblr

Tumblr is a "short-form" multimedia blogging platform. A favored stomping ground of college-age hipsters, amateur photographers, graphic artists, and people who just felt like making one, it's far less text-rich than other blogging sites. Users tend to collate pretty images and memes from around the internet on their tumblogs, with most memes also being popular on 4chan at the same time. They can also follow one another and reblog or like one another's posts, a system that encourages popularity contests. Themed tumblogs abound, from Fuck Yeah, Dioramas! to Lesbians Who Look Like Justin Bieber.

"Weblogs? Been there, done that. Facebook? It's full of kids. Twitter? That's so 2006, darling. No, the smart thing to be doing online these days is tumblelogging, which is to weblogs what text messages are to email - short, to the point, and direct."

—The Daily Telegraph

"For me, '...dot Tumblr dot com' has been gradually replacing ...would be a good name for a band".

—Xkcd 1025

Though Tumblr seems to be gaining popularity, it has yet to be overrun by celebrities like fellow New Media hubs Face Book and Twitter. Instead, it's populated by all sorts of Fan Girls, Hipsters, as well as vanguardists from every Hatedom imaginable. It's also known for its tacit encouragement of designers. Tumblr's interface makes it easy to set up a portfolio, and its support staff has been praised for running its Theme Garden, which features often minimalist layouts designed by users.

Harry Potter, Doctor Who, Misfits, Glee, Supernatural, Homestuck, Hetalia, shows from the Golden Age of Animation, Cult Classics, and any movie or show with a large slash following (such as X-Men First Class and Sherlock) have fairly large fanbases on this site. Like most places on the internet, Shipping is also a big deal.

This site provides examples of:

Animal Reaction Shot
Arch Enemy: With Face Book
- Alternatively, 4chan considers tumblr this. Especially /co/ due to yaoi fangirls and rampant shippers which they feel bring in the more annoying (to them) aspects of fandom and make discussing things besides Shipping a chore if not impossible. The vitriol got even worse once The Legend of Korra premiered and tumblr practically exploded in Korra love, fanart and shipping wars.
Ascended Fanon: Tumblr's own variation of the Fail Whale, the Tumbeasts came from this strip from The Oatmeal.
Berserk Button: For most users, "We'll Be Back Shortly", and for others, the Tumbeasts error page.
Character Blog: Ask Blogs (mostly drawn, but there are a lot of text-based blogs). Probably older than most visitors think but the majority of popular ones are for newer series. RP Blogs (either independent blogs or part of an rp group) are also popular.
Cool Car: lots of car porn.
Costume Porn
Crowd Song: No, really.
Deadpan Snarker
- Snark to Snark Combat
Design Students Orgasm: Averted with the themes, which are very minimalist, but played straight with the art posts.
Dueling Products: Fought with and has eventually took over Live Journal's spot as the fandom location on the internet. There are examples of small to medium size fandoms completely abandoning Live Journal in favour of Tumblr. One example is I Carly, which had a half-dozen or so active journals with regular discussion turn into ghost-towns, as the fandom quit en masse to join Tumblr instead.
Emo Teen: A good portion of the Tumblr demographic.
Fan Girl: A bunch of fansites following the convention fuckyeah__. Common alternatives are "hellyeah" or "heckyeah" if the person in charge doesn't want to swear in the blog title.
- Yaoi Fangirl: There is also a large yaoi fanbase on the site as well. In fact, the majority of the girls on there can and will ship any gay pairing as hard as they can, the more nonsensical the better. There's something of a running gag on the site that, on Tumblr, there is no such thing as heterosexuality.
The Fashionista: A large portion of the Tumblr community.
Food Porn: Many blogs post richly-colored photos of food for seemingly no reason.
Friendly War: On May 2012, Europeans liveblogged about Eurovision 2012. America declared a Banana War on the Eurovision posts by reblogging bananas.
A Good Name for A Rock Band: As pointed by Xkcd.
Gorn: There's quite a few gore blogs for some reason. And by gore, we mean real life gore not movie gore. Though there's tons of that too.
Goth: Many of these, perky and otherwise.
Hipster: As seen in the page image, a lot of the people on Tumblr are considered hipsters.
Link Blog: What tumblogs often become in practice.
Mad Libs Catchphrase: As noted, single topic tumblogs that catalog or reblog a single focused topic, frequetly fannish, are often titled "fuckyeah(subject)" or the more mild "fyeah(subject)", "effyeah(subject)", "hellyeah(subject)", or similar constructions.
Moe Anthropomorphism: Tumblr-tan, who's frequently shipped with Anonymous thanks to the late 2010 drama between the sites.
NSFW: Dear lord is it not. Best not to do searches while at work or around the family, less you run into porn (of all shapes). Fortunately, there is an app out there to save you from the nasties or whatever you don't want to see. Except for the things that were not tagged correctly.
Political Correctness Gone Mad: Sorry Live Journal, you've lost the crown.
Perverse Sexual Lust / Rule Thirty Four: There's LOTS of porn blogs..
Picture Pastiche: A lot of users post iconic paintings, especially if they're Pre-Raphaelite or Neoclassical.
Ridiculously Cute Critter: The Tumbeasts, not to mention all the pictures of cats, puppies, and other assorted animals frequently posted.
Serious Business: Gifs. Losing a follower is often treated like a death scene in one's favorite movie, with .gif spams of Heroic BSODs.
- As mentioned in the description, shipping is also very serious business at Tumblr.
Soapbox Sadie: While not as big a presence as amateur photographers, it's very hard not to run into social justice activists on Tumblr.
There Are No Girls On the Internet: Averted so hard with this site, where a large majority of the site's fandom-based tumblrs are run by females. Most of the straight porn blogs are actually run by girls.
Troll: Oh goodness, where to begin?
Urban Legend of Zelda: It'd take to long to list all of the widely believed hoaxes started and propagated on tumblr. A 'if you don't reblog this your blog will be deleted' hoax gets passed around every few months.
You Are Not Alone: Many promote this as their advantage over Facebook.