"In that direction," the Cat said, waving its right paw round, "lives Anonymous: and in that direction," waving the other paw, "lives tripfags. Visit either you like: they're both weeaboos." "But I don't want to go among weeaboos," Alice remarked. "Oh, you can't help that," said the Cat: "we're all weeaboo here. I'm weeaboo. You're weeaboo." "How do you know I'm weeaboo?" said Alice. "You must be," said the Cat, "or you wouldn't have come here."
Online forums that exist expressly for the purpose of posting images and/or discussions. They usually have a variety of sub-boards, each with its own focus. Unlike most forums, threads are never archived by the site, so if nobody posts in one for a while, it will eventually be deleted.
The imageboard as it's usually thought of today began in Japan. Futaba Channel, a spin-off of the popular text-based discussion board 2-Channelnote Officially pronounced "Ni-Channel", but most English netizens are comfortable with just calling it "Two-Channel" (2ch) is probably the best-known. Sometimes the blanket term 'wakaba style' board is used (wakaba referring to the board software that runs the board), traditionally allowing anonymous posting with a self-enforcing theme and standard that hopefully keeps it from becoming too mediocre.
The best-known in the US is probably 4chan, created in 2003 to serve as an English-language version of Futaba Channel. Especially among Americanotakunote Or, although the term is used more in a negative sense, "Weeaboo", it's quite popular for the generator of memes and, due to anonymous users and loose moderation, extremely variable quality; for these reasons, one could see imageboards to be the antithesis of social networking sites such as Twitter and Facebook.
Most American wakaba boards trace their heritage to 4chan, as alternate boards proliferated when 4chan went offline in its formative years. The successful ones tend to cover more specific niches, like Meganekko or sad girls in snow. Or guro hentai. Or lolicon. Or guro hentai with underage meganekkos in snow. Or guro hentai with underage meganekkos in snow weeping profusely over image boards. Or... you know what, let's just stop talking about it.
The only real standing rules of just about every imageboard site in existence (besides specific topic rules for subforums) is that its users can't post anything considered illegal in a site's area of hosting (many admins turn a blind eye to things like unauthorized filesharing, however). Dodgy to outright highly illegal material is occasionally posted anyway just for the pleasure of subverting this rule; mods unsurprisingly counter this with anything from warnings to reports to the FBI.
What many imageboard sites have in common is using the same distinctive layout and interface from 2ch: there is a sidebar either on the left, bottom, or top (but never the right) that lists each board on the site in a simple URL theme (usually a contraction of their topic name), and to the right of this is the actual site content. Most boards are also set up fairly similarly to 2ch, (/v/, /m/, /tg/, etc) so you can usually count on wholly different sites to have the same general setup.
Not to be confused with our own Image Links Wiki, or Image Booru.
Notable Imageboards (every link below should be considered NSFW unless specifically mentioned otherwise):
While not an imageboard itself, The Overchan V.2 used to maintain an (as up-to-date as humanly possible) list of every English-language imageboard in existence (including furry imageboards and text-based 2ch-esque boards). It was also the closest thing to a worksafe link from this point forward. Two replacements fortunately have popped up: AllChans and Overchan v3
The aforementioned Futaba Channel, a spinoff of the text-only, and far more infamous, 2ch. Take note that unless you live in Japan, you can't post at either board, though you're free to lurk. This is to prevent crapflooding and DDoSing from foreigners outside of Japan. And even if you could, it is much more chaotic, vitriolic,somehow more organized than 4chan, and farless tolerant of newbies than 4chan is - for a board already disdainful of newbies. Most of the imageboards frequently have discussions and images (or ASCII art) that are unrelated to its intended purpose and spam is basically omnipresent. It has a lot more boards than 4chan and churns out memes, trolling, racism (to the point where there is an entire subboard on 2ch/an dedicated to bashing Koreans), and .gifs at an even faster rate. Unlike its western counterpart, it still maintains its guro boards to this day.
The also-aforementioned 4chan, which hosts boards dedicated to just about every generalized subject you can think of (and a few specialized subjects, as well), is home to the self-proclaimed "final boss of the Internet" (the Random [Bullshit] board, aka /b/), and is the starting point for about half the memes in the various subpages of the Memetic Mutation article. Humorously enough, 4chan was created by a bunch of regulars from Something Awful's anime subforum, a fact that is best left unmentioned on both sites. Has its infamous, luckless spin-off, 7chan, Which has its own spin-off, 99chan (see below). The users consider them 'better' than 7chan - and sometimes even 4chan.
/a/ (Anime & Manga) is basically the same as /v/ (see below), but with anime, and "live action" television shows that are distinctly rooted in, or based off of an anime or manga series. Mostly discusses the more popular series, and upcoming shows they think will become popular. New anime gets released at a much faster rate than American cartoons, so there's usually plenty to discuss. Sometimes when the mods feel like trolling, the board title gets changed temporarily to "Animu and Mango" or, even worse, a Naruto-specific board with a Naruto video autoplaying at the top and a giant image of a black man as Naruto. This caused much Drama, and spawned a new breed of Naruto fans on /a/. (who are sometimes blamed for shitposting)
/adv/ (advice) is for advice, mostly relationship, and about as good as you can expect from a random group of completely anonymous people on the internet.
/an/ (animals and nature) is mainly full of topics about animals, both wild and domesticated. Topics like "What's your favorite dinosaur" or "How do I take care of my pet" are common. Animal cruelty is not allowed though, and you will be banned if you post it.
/asp/ (alternative sports) is for discussion of sports that aren't major, professional ones. Mainly become the home for Wrestling after it was kicked off of /sp/.
/b/ (random) is not all of 4chan, everyone just thinks it is. There are no real rules in /b/, so people are free to post whatever non-criminal material they want. In practice, that means a lot of porn, pictures, and discussions that can only be defined as, well, random. Notably, it can have, and undoubtedly has had, every single one of the other boards' topics discussed on it, with the main difference being more chanspeak. Another type of popular threads involve "posts ending in x will decide y", referring to the post number, which are treated with mixed reception. /b/ is also the source of what might be called chanspeak, which is a dialect of net slang that is best described as mixture ofAcronym and Abbreviation Overload and Cluster F-Bomb.
/biz/ (business & finance) was created to offload the cryptocurrency threads that were clogging /g/ for some time. Here, /biz/raelis talk about stocks, the state of various businesses, wages, and other money making ventures.
/c/ (cute anime), and /cm/ (cute men) are work safe boards for cute animated things. /cm is for cute men (animated only), and /c/ is for everything else that's both animated and cute including girls, couples, and animals. It has quite a few chibis because of that. /c/ is regarded as a place for anime fans to go if they just want to post/look at pictures without all the drama and trolling that /a/ discussions tend to generate.
/cgl/ (cosplay and egl) (one board, egl is part of the title) where people show off the cosplay they work on, talk about conventions they went to and what they cosplayed as, and general cosplay tips. They're the place to go if you need help on a cosplay of your own. Be warned, however, that on off days /cgl/ is one of the most vicious hotbeds of cosplay drama on the entire internet, with frequent callout threads, a dedicated elitist membership that frowns on "easy" cosplay (especially Homestuck cosplay), and white knights fighting for big-name cosplayers.
/ck/ (food and cooking) is usually filled with a mix of delicious recipes, people asking for delicious recipes, and general cooking tips. Speaking of tips, never, under any circumstances, browse /ck/ on an empty stomach.
/co/ (Western Animation and Comic Books) is the Western version of /a/, for all non-Asian comics and cartoons. /co/ can get kind of obsessive about shows and girls it really likes. When a new show it likes starts airing, the board usually becomes flooded with topics about it, which eventually resulted in the rule that only one My Little Pony thread could be active at a time, after people complained. Unlike /a/, though, it's a lot more controlled. Warning: don't discuss anime. Has a reputation for being welcoming ("/co/ is love"), but that reputation's slowly been eroding, after a flame war drove off most of /co/'s dedicated artists and /co/ flew off the handle about My Life Me. On the other hand, it is usually far more civil, on-topic, and troll/drama-free than /a/. One can find plenty of scans of comic books here.
Apparently the one-thread policy didn't seem to be work as far as My Little Pony is concerned, as individual pony posts and threads would still appear all over the boards, drawing the irk of various 4chan-goers. During the February 2012 reorganization of the boards, one anonymous poster suggested that an MLP board be created to confine pony-related posts, but it wasn't until a plea from an MLP fan against it implied such a board would ruin the fandom (i.e. at /vp/) that the admin made up his mind. Thus /mlp/ (Pony) (see below) came to be.
/con/ A rare board that opens up whenever there is a large 4chan-related convention took place, which happens like ever six years or so.
/d/ (hentai alternative) is for hentai that's a little bit... different. Girls with penises, traps, monster girls (though in and of itself this can also be found on /h/), girls with monsters, bondage, tentacles, and anything else in that general category. Bestiality (of the non-monster variety), guro, scat, or anything generally seen to be "extreme" is not allowed, however. That means it's perfectly okay to show a girl having sex with a minotaur, but showing her with a bull is no good. Remember, /d/ is for dickgirl.
/diy/ (Do-It-Yourself) is for do-it-yourself projects, whether it's fixing something broken or creating something from scratch.
/e/ (Ecchi). is the softcore porn board, separating it from /h/, which is for hardcore images. Ecchi material is suggestive and often times cute, but it is still an adult board with adult material that does allow anatomically-correct nudity.
/fa/ (Fashion) is a board where posters or /fa/ggots talk about clothes, accessories, outfits, and other fashion trends. Has a nice, if hipster-oriented, thread detailing how to tidy yourself up and look presentable and at the same time comfortable.
/fit/ (Fitness) is a board dedicated to healthy living and exercise routines, although the main focus seems to be on strength training. Posters will frequently joke on how obsessive its members are with the littlest of details in fitness routines like squats and oats, and maintaining "gains," and despite all of their efforts somehow, they still cannot get girlfriends. If you manage to get pass the broscience and trolling, a few good fitness tips can be found here, especially in Harsh's Worksheet.. No homo.
/g/ (Technolo/g/y) is dedicated to mainstream tech discussion. Widely dominated by desktop computers and audio players trollfests (though there are ocassions where an exceedingly good thread comes out, for example, the sat-comms Q&A), this board is known for the insane amount of Windows vs. Mac vs. Linux threads, the endless desktop/battlestation/guts thread, the insane amount of trolling and newbie baiting (deleting system32 and installing Gentoo as the most notorious examples), nVidia vs. ATI/Intel vs. AMD/Android vs. iOS, C# vs. Java vs. Python (actually every tech rivalry known to man will have at least one thread per month), hating on audiophiles, hating on Arch Linux (and every distro in existence), arguing about anything, and the occasional genuine help thread. Its main contributions are the Stallman copypastas, the 1.7 meme, and IT'S OVER, _____ IS FINISHED. On a more positive note, the daily programming threads and the occasional tech community thread (mostly discussing jobs in the tech industry) are what saves this board from extinction. Has it's own wiki of information here.
/gd/ (graphic design) is for discussion of graphic design software and computer-aided graphic design techniques (i.e, 'photoshopping').
/gif/, a board for posting looping animated images, or GIFs. Since the creation of /wsg/ below, however, it's only really ever used for porn.
/hc/ (Hardcore) is dedicated to hardcore pornography.
/hm/ (Handsome Men) is for real-life pictures of men, be it safe or pornographic (all of which is of a homosexual nature).
/hr/ (high-resolution) is for very large images in general. Often a good place to look for wallpapers, though this board can and often does veer on the NSFW side of things.
/int/ (international) is where people from around the world are allowed to post in various languages. A person's country is indicated by a flag in the top right of the posts. Sometimes, unfortunately, this board attracts as much race-warring and racism as /pol/, as it is the originator of the phrase "Remove Kebab" referring to turkish people.
/k/ (weapons) is about weapons. While firearms tend to be the most talked about, swords and other melee weapons, armor, and all kinds of military hardware and equipment are also covered here. Topics about hunting and wilderness survival pop up occasionally as well, along with the more inflammatory gun control debate threads and hypothetical "survival" situations that annoy veteran posters to no end. While they generally don't like video games, STALKER threads tend to get a free pass (to the point of becoming a meme).
/lgbt/ (Lesbian, Gay, Bisexual, & Transgender) is for the respectful, work safe discussion of LGBT lifestyles and the LGBT community. Aside from /pol/ shitposts, it's usually quiet and usually drama-free.
/lit/ (literature) is for discussing professional stories. That means fanfics are not allowed, though they do get posted somewhat often (mostly to piss off /lit/). Other than that, the board talks mainly about their favorite books, and is a great place to go if you want a recommendation for something to read. Be warned; at their worst, they can be the /v/ of literature, but at least they are on topic.
/mlp/ (My Little Pony: Friendship Is Magic and other pony-related media) was added by moot to give the pony fans on 4chan a place to post without angering some of /co/'s residents. While relatively recent, /mlp/ has already earned a reputation in the eyes of the fandom as being essentially the /b/ of the bronies (and in all honesty, not without good reason).
/mu/ (Music) is for discussing all genres of music, especially the ones you haven't heard of. Much like /tv/, the /mu/tants are not very welcoming, as they are obsessed with arguing or trolling over which music is "patrician" and which music is "plebeian". /mu/ is obsessed with bands/artists like Neutral Milk Hotel, Animal Collective, Radiohead, Kanye West, and Death Grips. They are also obsessed with music review site Pitchfork, Italian expert Piero Scaruffi, and reviewing b/vlog The Needle Drop. The /mu/tants love bragging about their musical tastes, either by their last.fm statistics or custom created Top 50 album charts. Occasionally, there are "share threads", in which people would post download links to various albums. The /mu/tants love their feels and will remind you daily about tfw no qt3.14 gf. Once you get past the shitposts and the trolling, there are a decent number of threads, including a number of good Essential charts.
In early spring of 2013, fans of K Pop idols who used to post in /vg/ were "banished" to /mu/, since those threads tend to fall under "music related". These folks exists in their own little ecosystem, rarely visiting other threads.
There have been a few Q&A sessions with a few Popular Musicians. /mu/tants usually don't like these thread since moot never picks Artist/Bands relevant to the board. Andrew W.K. was the first and it was very successful to say the least.
There's also /n/ (transportation), which is a very slow (for 4chan) board that's generally 95% bikes, 2% trains, 2% planes, and 1% people lost on the way to...
/out/ (outdoors) is for discussions about hiking, camping, geocaching, orienteering, gardening, etc, and other traditional ways of enjoying the great outdoors.
/p/, the Photography board: Containing an almost paradoxical hatred for Hipsters and post-process while simultaneously gushing over vintage camera equipment and Photoshop gurus while, at the same time, supposedly ignoring "gear" threads and "how to " threads, /p/ has the distinction of being possibly the single most concentrated collection of image retouching talent on the entire internet. When they aren't showing off their retouching ability (or mocking each other by photoshopping realistic genitalia into one another's photographs,) /p/ tends to entertain itself by way of vast galloping flame-wars over camera equipment and photographic styles. Just, for the love of whichever god you worship, if you post your images to /p/ remember to resize them to 1,000 pixels on the longest side. You really don't want to see what happens if you don't.
/po/ (papercraft and origami) isn't very populated, but they're generally pretty helpful to anyone who shares their interests. Full of people showing off their awesome works of paper and stencils, and often containing simple papercraft guides.
/pol/ (Politically Incorrect) is the board for politics, current events, and general debate. Much broader in scope than the board it supposedly revived, /n/ (News), which was dedicated to news only. Revived due to user demand now that election season is underway. Flamewar central, with many extreme opinions that would earn bans on other forums duking it out. Is also filled with threads debating which race has the most attractive women, and unironic racist posting (Jewish conspiracies and the inferiority of blacks are a common topic). Ron Paul is perhaps the most beloved of American politicians by /pol/. Incredibly hated by other boards, due to /pol/ users spamming other subboards like /k/ with anti-Israeli/anti-Semitic threads. In fact, other boards have increasingly begun parroting opinions similar to those found on /pol/, although /pol/ denies any involvement and often claims the only opposition to /pol/ are the infamous Tumblr/Reddit social justice crowd.
/r/ (Request) is where it is possible to request where to find each and every one of the above topics. Much porn hunt abounds. Infamous for the great majority of requests going unanswered.
/r9k/ (Robot 9001) is a board based off Randall Munroe'sROBOT9000 idea. In practice, it's kind of like /b/, but with less porn and dead memes. Tends to have (relatively) intelligent discussions about anything and everything. A good deal of the time the board is filled with misogyny, "feel" threads and ronreyness. The few remaining meetup threads and rate me threads belong in /soc/.
/s4s/ (Shit 4chan Says) was originally an April Fool's prank meant to mimic the subreddit "Shit Reddit Says"note SRS is infamous for being an extremely vitriolic subreddit that mocks misogynistic, racist, and homophobic comments from Reddit. Reddit itself either sees them as irritating, humorless, easily-offended killjoys, or a useful antidote to stupid posts on Reddit but due to it being NSFW as well as including things long gone from /b/ (No Forced Anon, dubs, etc.) it has now become a permanent addition. /s4s/'s main call is dubs (when a post number ends in repeating digits), dedicatedironic shitposting and forcing various memes (such as Kek or Blimp) and stealing other board's gets (Major posts like a board's 100,000,000 post or post 34567890). The board has an interesting subculture, as gets are central to the board, and they have a large list of colourful characters, as well as, even it's own board newspaper! It's also property of Gippo Dudee, kindly fuck off.
/sci/ (science and math) is for people interested in science and the latest scientific advances, or needing help understanding a math problem they don't get or a science project they just can't make work. Also home to a great many science vs. religion arguments (surprise surprise).
/soc/ (cams & meetups) was started as the board for anything not nerdy (it was originally named Social for this reason), but quickly devolved into a bizarro combination of /r/ for specific types of porn and meet-ups for one-night stands and phone sex. How truthful they're actually being about this is probably best left uninvestigated.
/sp/ (sports) takes the already heated topic of sports fandoms and adds that special 4chan touch. /sp/ hates all teams in general and your team specifically, though local fans will often show up to defend their team when the arguments get really heated. The big draws are game threads following and commenting on the action live (good games for the major sports can require multiple threads that hit the limit, and major playoff games are guaranteed to go something like 7-10 threads long). Thanks to the large number of users all over the world, /sp/ is one of the few boards to have distinct variations. There is the Soccer and Lad banter filled "yuro /sp/" and the Football/Baseball/Basketball and various other sports filled "murikan /sp/". While the two sides tend not to agree on a lot of things both are well known posting lots of Power Rankings threads, Feel Threads, Mila Kunis threads, Ian Terry threads and plenty of Tony Kornheiser which has caused many anons to rename /sp/ to the "Shit Posting" board. /sp/ was deleted once in the early 2000s but later restored.
/tv/ (Television & Film) It's /mu/, but with movies, with all the same critic worship, hipsterism, and plebian flame wars. And celebrities. Lots of them. It's one of the few places where you can freely post pics of women feet or compliment teen or child actresses in unambiguous ways without being called a creep, in other words, it's a haven for pedophiles and creeps. /tv/ tends to be obsessed with certain shows, like Breaking Bad, Game of Thrones and, back in the day, LOST. Generally, /tv/ is a good place to discuss new episodes of various shows, if you can stomach waifu stuff and occasional /b/ tier comments. However, with movies, /tv/ may be very picky, and it will most certainly hate vast majority of the new ones (go ahead, try talking about The Dark Knight Rises - "for you" is still widely joked about to this day). Wrestling and some anime movies go also go here. Like /fit/ and /r9k/, /tv/ will remind you of the daily tfw no qt gf to go to the movies with.
/u/ and /y/, the Yuri and Yaoi boards. Both are known for their tendency to see homosexual relationships where none exist. Of course if they didn't, they wouldn't have all that much to talk about. This means they talk a lot about shows like K-ON or Kim Possible, which have no explicit (or really even implicit) homosexuality, but a fan base that really likes to pretend they do, as well as more explicit cases of homosexuality. Neither one moves very fast, so it's not uncommon to see a thread linking to 4 or 5 previous ones with the same topic that no longer allow images.
Several members of /v/ had created the wiki site "/v/'s Recommended Games" as a response to many threads asking what to play next. The community there is a lot nicer too. /v/ itself seems to have disowned it after Reddit started using it.
/vg/ (Video Game Generals) is a "spinoff" board of /v/. It's meant to offload the "general" threads clogging /v/: long-term oriented, recurring threads focusing on a specific video game that get recreated as soon as the old thread dies (750 posts, after which posts stop bumping the thread and it will soon 404). Threads receive their own, board-style abbreviation (such as /mhg/ for Monster Hunter General, or /sgg/ for Skullgirls General). Tends to attract a lot of posters who mainly post on /a/, thus contributing to some generals being derailed by large amounts of anime-related posting. Despite this, and while it tends to vary from thread to thread, /vg/ is, in general, far, far nicer than /v/.
Another board borne of /v/ overload is /vp/ (Pokémon). Pokémon discussion clogged up the /v/ board so badly, they made another board, just for Pokémon. That should tell you how popular Pokémon is there.
Yet another spin-off of /v/ from March 2013 is /vr/ (retro games), for the discussion of classic, or 'retro' games. Retro gaming means consoles, computer games, arcade games (including pinball) and any other forms of video games circa 1999 and earlier, but sixth generation is not considered retro, thus rendering the Dreamcast "not retro". Previously in a one-month tryout phase, it's meant to offer discussion of retro games without the flamewars and bickering of /v/. It is now a permanent board.
/w/ (anime wallpapers) is for very large pictures related to animes, to be used as wallpapers on computers. They don't like people requesting Wallpapers.
/wg/ (wallpaper general) is for very large pictures not related to animes, to be used as wallpapers on computers.
/wsg/ (Worksafe GIF) is for... well, worksafe .gifs. Great for reaction images. Being 4chan though, probably should not be viewed at work, as moderately NSFW images will still be present.
/x/, (Paranormal; as in The X-Files) is the creepy, scary, paranormal, and general "weird shit" board. /x/ is the origin of a great deal of the "creepypasta" floating around the Internet and memes based on crappy ones like "AND THEN A SKELETON POPPED OUT" and "THEN WHO WAS PHONE?", which eventually led to the creation of SCP Foundation. These days, however, it's mostly a place for neo-pagans and hipsters to discuss dreams and psychic powers.
/3/ (3dcg) is for 3d modeling, sculpting, and so on. By far the slowest board on the site, there are often threads that have been active for nearly a year. Relatively docile and calm compared to the other boards. Doesn't like porn or people who ask how to make porn.
420chan, created as a result of one of 4chan's longer downtimes, is a site specifically geared towards drug users (with several boards dedicated to different types of controlled substances; the site refuses to allow people to directly buy or sell drugs through the site itself, though). It also has several non-drug-related boards, including the site's most second-most-visited board, /wooo/. /wooo/ is one of the most well-known Professional Wrestling imageboards on the 'Net, to the point where WrestleCrap considers the board their Arch-Enemy and forbids their Message Board users to mention it. (420chan's most visited board is, as you might expect, /weed/.)
fchan, which is the most well-known furry (primarily erotic furry) imageboard out there; although assumed to be created as a response to 4chan's infamous "April Fur's Day" pranknote The notoriously anti-furry 4chan created a furry board, /fur/, on April Fools' Day...but then kept it up for a few more days. Then on April 4th everyone who'd posted on /fur/ was banned from the entirety of 4chan., it was actually in existence for a while prior to it (and was created as a result of 5chan — which hosted a couple of furry-based boards — dying). The site set something of a standard for future furry imageboards by segregating content into different boards (one for female-only art, one for male-only art, and so on); it also marked the beginning of the term "DNP" ("Do Not Post") in the Furry Fandom, due to the list of artists who asked that their work not be posted on the site. fchan's heavyhanded moderation and large DNP list led to several furry imageboards coming into existence to counteract fchan's perceived stupidity, the most notable of which are:
Lulz.net, which is sometimes referred to just as /furi/ after the site's main board; it is pretty much always EXTREMELYNSFW, and not always because of furry porn — and not always because of porn. Many of the board's threads are about gore pictures, grossout images, trolling, and extremely vitriolic politics. There's also more furry-hate on the site than /b/ and Something Awful combined. Even the board's regulars will often admit that the site is basically "/b/, but with less furry porn". If you go in without Adblock prepared beforehand, it's also a great stress test for your antivirus application of choice.
55chan, a Brazilian imageboard. Before the site died, it used to attract a good number of functionally illiterate users, commonly assumed coming from the social networking site Orkut. Those users would usually flood the boards with bland topics and requesting the other users to raid their enemies' pages on Orkut. The moderation eventually put a stop to this by enabling a filter that asked the user to copy a simple sentence using capitals and punctuation without using the copy-paste command; only once this had happened would a user be allowed to use the boards. That filter was enough to fend off the vast majority of the problem users. Its replacement is now BRchan.
7chan, an imitator of 4chan and purportedly luckless when it comes to actually being recognised. Usually spread by annoyed ex-/b/-tards fed up with the decline of 4chan. Boasts most of the content 4chan does as far as subboards are concerned. Due to lower visitor numbers tends to be less chaotic. Really doesn't like Something Awful or the notion it's a 4chan snowclone. Maintains a Lolicon board (among other things) but will ban anything that even smells funny of CP.
888chan was the imageboard chiefly used by Project Chanology, an Internet-based movement based on the Anonymous "culture" borne from 4chan's /b/ (the group has no defined leaders, and most of the members of the various Chanology subgroups do their best to remain anonymous) which was (and still is) dedicated to "fighting" the Church of Scientology. (Project Chanology itself has been going for more than two years as of this writing; it has used several different imageboards as their base, with 4chan's /b/ being the original starting point of the movement.) As of 2013, 888chan now has a board for lolcow discussion and harbors the remnants of 789chan's users
Desuchan, the result of a certainmeme becoming too big and obnoxious for the other imageboards to stand. ~desu (pretty much worksafe) It also has its fair share of spinoffs, mostly as backups during downtimes.
Krautchan, pretty much THE German imageboard. Became famous in the wake of the Winneden school shooting, when the media fell for an extremely obvious fake post announcing it (a real but completely unrelated post photoshopped). Has an /int/ board. Its humour consists mostly of intentionally bad and literal translations of english memes and imageboard slang. (Beweis mich falsch, fappieren)
Another British Image Board is B3TA, which in addition to message boards, also has weekly or so Image Challenges, quizzes, movies and games. While the vast majority of the userbase are okay folks and the image challenges bring out funny images.
plus4chan, originally started as an offshoot of 4chan prime's /co/ (Comics and Cartoons) board, has since grown into its own standalone site with a very tight-knit userbase. Much of the content is still /co/ related, but there are also boards about anime, video games, cooking, music and television, and Homestuck, among others.
99chan. Elitist as hell, and damn proud of it. 99chan is even slower than 420chan, but has a huge variety of boards. Expect to be banned if you post demotivators, memes, or if the many mods are feeling bored. Most of the humor on the site revolves around inside jokes and self-deprecation. Practically everything is decided on the IRC (better known as the "circlejerk"), which is self-admittedly populated entirely with pseudo-intellectual gay Canadian alcoholics. Tends to have a "sekrit club" mentality, so if your post smells even faintly of 4chan, expect to be banned.
MikuChan is an image board dedicated to Hatsune Miku and other VOCALOID characters/voice banks
789chan, an imageboard with a focus on technology. It is, however, most well-known for its /cwc/ section, which, of course, focuses on Christian Chandler of Sonichu fame. Despite the title, very few threads are about Chris, and generally discusses several other people on the internet that users don't like. Was shut down on November 2012.
Nido is a Chilean imageboard. Even with the NSFW material that pops frequently, it's pretty lighthearted compared with most of the imageboards it tries to emulate. With a permanent hatred of all the people that commit spelling errors (they have an explicit rule against it, and if you post with any spelling errors you will get banned), it is the most active imageboard from that country to date. It was made by some users unhappy with 6-chan (another Chilean imageboard) when that had legal issues. Most of the boards are locked for people that don't have a Chilean IP address, but they have an /intl/ (international) board that is open for outsiders.
Shrekchan a strange and somewhat active board with a focus on all things Shrek. Mostly full of shrek-themed images and NSFW greentext stories with a... unique version of chanspeak. Yes, it's ironic... Probably.