4chan was born of two cultures - the user-base of the English language internet discussion forums and the culture of Japanese image-board BBS (Bulletin Board System) systems. The netizens of both sides had their own particular characteristics but a common origin: a mass switch from USENET to BBSs. Japanese internet groups were composed of tight-knit communities of geeks who already had their own meta jokes (memes) by 1996, while the Western-hemisphere had hacking groups dating back to the 1980s, most notably Cult of the Dead Cow (cDc), which formed its own community based on active projects including the 1995 campaign against the Church of Scientology.
In Japan, internet culture began to form out of people who used Home Parties circa 1995. The "underground" Internet, the first sites to leave USENET, was composed by technology and hacking enthusiasts. What would become textboard culture and ultimately engulf the entirety of Japanese internet culture began with one man: Masayuki Shiba.
Shiba started a Home Party Website (ホームパーティー) in 1995 called Ayashii World (あやしいワールド), via provider Nifty-Serve. The site was dedicated to the controversial underground game called Kasumigaseki, based on the Tokyo Subway attacks. While it was an unrelated, short-lived site, the name stayed with him. In 1996, Shiba comes in contact with a site called Japan Lolita Complex Graphics (日本ロリコングラフィックス), dedicated to highly sexual cartoon depictions of teenage girls and ran by Duke Pedo (ペド侯爵 - Pedo Koushaku). JLCG used a variety of free Internet hosting services and an anonymous BBS. This greatly influences Shiba, and he recreates Ayashii World as one of the first BBSs on the Japanese Internet, operating with anonymous posting and free web services (In this particular case, Mails by Postone, Hosting by Tripod, registration free; anonymous BBS code by Digital Eden. Yes, anonymous culture was literally born out of some Jap's desire to post CP). The original topics of Ayashii World were mainly Lolicon, CP and Geek culture discussion like cracking and SJIS (ascii images created using Japanese fonts) art. The main appeal of the sites would be anonymous discourse – The possibility of not being identified led to a raw, no-holds-barred discussion between the "Nanashii" (Japanese for nameless) people who would come to the boards to distance themselves from the norms of deferential Japanese culture.
Ayashii World would proceed to become an important center of the Internet. Further into 1996, one of the first Underground sites, dedicated exclusively to technology and hacking, A Portal to an Underground (地下道入口, Chikadou Iriguchi), closed. The majority of its userbase would flock towards Ayashii. Its users introduced warez and MP3 files to the general net and the contributed greatly to making Ayashii become a household name in the Japanese underground, with many "sister" sites adopting the Ayashii World system. The web of similar sites having "AyashiiWorld#" as a prefix would collectively be called the Nameless World (Nanashii Warudo). Common traits among Nanashii World sites would be that the admins would begin their name with "Kanrinin-san" (Mr. Admin)", The users would come to be fond of absurd humour and visual memes such as the Giko-Hanyann or Giko-Neko (Giko-Cat), a small SJIS cat with a speech bubble that says "Itte Yoshi", which depending on the typing system may mean "Please Leave" or "Please Die". The speech bubble itself also enabled them to express short sentences. Ayashii would change BBS host from Digital Eden to Kenjinkai, which only let them write one line, and after Kenjinkai drops them, their own code. Important things would happen in Ayashii, such as hackers posting about their important hacks and later getting arrested or the leaking of the name of the Sakakibara killer, which would throw the Ayashii World sites into disarray and get many BBSs to crash or temporarily go offline.
In Ayashii conflict between the old and new userbase began to arise and Shiba decides to divide the BBS in two, one called 97, for general topics, and another called 2000, for technology. 2000 would soon become the gesu (Scum) board, because of their habit of planning and participating in forum invasions, raids and hacking, including popular sites from RL (real life) companies. Their attitude would go on through the years, in a reminiscent way of the raid culture 4channers pertained during the days of 2006 and 2007. The split did not quell the conflict, however, and in late 1996 the users of 2000 would eventually create their own site, called Guess BBS. 2000 would be the birth Japan's legendary cracking group, GUESS.
In 1997, the first imageboard, Licentious Notice Board, is created by Mr. Fujinami. Its userbase excels at image collages and comedy and the site becomes a fad on the Japanese Internet. However LNB is short lived and no new imageboards are created due to a split between its userbase. LNB's personality and methods of posting made it in many ways a forgotten precursor of 2chan.
The end of Ayashii comes from the hands of Mr. Alice, Guess BBS's administrator. On March 1998 he codes an auto-posting script and uses it to spam Ayashii. Enraged, the userbase of Ayashii retaliates and hacks Guess. Despite Shiba's attempts at stopping them, later during April they leak Alice's dox (real name and location) and manipulate images of him. Scared due to the possibility of a lawsuit, something that is very costly in Japan, Shiba shuts Ayashii World down. The Ayashii World is left without its core for some weeks, until it is rebuilt by Shiba as Ayashii World Main BBS (あやしいわーるどメイン掲示板). Some months later, he abruptly closes the BBSs, tired of the site's hostility and incapability to deal with new users. This time, the whole collective of sites is thrown into complete disarray. Many users flock towards the Ayashii World sister site @an unofficial shelter purpose (@退避用非公認), declared the new main BBS. However, some weeks after Shiba left, Amezo BBS, a small part of the Nanashii World founded by Mr. Amezou on 1997, implements the floating thread system, dependent on aging (posting to bump a thread to the top of the list) and saging (posting but not bumping the thread). In contrast to tree pile-up style, where users would see most the recent replies to threads on the front page and reply to those replies, which made threads hard to follow, the floating thread system was easy to manage and understand. Amezo BBS quickly rises through the ranks, eventually becoming one of the biggest of the Ayashii World.
The same year, Hiroyuki Nishimura, copying Amezo, creates 2 channel (2ちゃんねる – Ni Channeru - The Second Channel, in honour to Amezo being the first), abbreviated as 2ch. 2ch's population would retain many cultural trends of Ayashii World, but it would gradually see an increase of Otakus in their userbase. Otakus were still mainly shunned in Japan, and Shiba and his users were not an exception. An animosity between both userbases begins to rise. Amezo eventually dies due to vandalism, and it is later revealed that Hiroyuki was heavily involved in spamming Amezo. Mr. Amezo tries to compete with 2ch by founding 1ch.tv, but strict posting standards and the later introduction of a fee for posting made the site unpopular. 2ch would create a peculiar board, /news4vip/ - News for VIP. An equivalent to /b/, VIPPERs would form a very distinct culture, fond of absurdity and SJIS art. Hiroyuki would have a second that usually patrolled /vip/, Nakao Yoshihiro (handle name 'Night Shift ★' and 'FOX ★'). His personality itself would eventually grow to become a meme within 2ch.
2ch would come to antagonize Ayashii World in many ways. Trolling, spamming, claiming Ayashii memes as their own and using Ayashii services without permission. Animosity would explode into hate when a thread popped up in Ayashii REMIX detailing all the attacks. Ayashii Worlders would script spam 2ch until it crashed. Hiroyuki personally apologizes to them in the thread, and later at the main site Ayashii World II. However trolling between both sites would keep on for years, a common insult from Ayashii Worlders to Nichanners would be "Tantsubo' (痰壷).
Within a few years, 2ch would go on to become a massive cultural phenomenon in Japan, achieving mainstream appeal. The possibility of unfiltered discourse fitted perfectly with the Japanese cultural tendency of the in and out personalities – a Japanese person must never show their opinions and beliefs in public, which should only be expressed in the house or with one's most trusted friends. 2channel would also become quite influential: Things like the movie Densha Otoko was based on the real story of a 2ch NEET (Not in Education, Employment or Training) who found himself on the good side of a girl but did not know what to do, so he asked for help on 2ch and the users of the site helped him win her.
By 2001, 2ch began to fall apart as data transformation bugs threatened to render the entire website unusable. Users began to warn of the coming apocalypse while volunteers from across Japan worked to find a solution. On August, its users make a backup BBS: 2chan (Futaba Channel - ふたば (双葉) ☆ちゃんねる - Futaba Channeru). 2chan, however it was not just a clone site. It implemented a handcrafted imageboard code called Futaba. For a while, 2chan would serve as the alternative hub for nichanners whenever 2ch crashed, but eventually it formed its own distinct culture and drifted apart. 2chan was not the first imageboard, however imageboards were a pretty rare thing, and many similarities can be drawn between older imageboards and 2chan. 2chan and 2ch would come to greatly surpass the Ayashii Collective in terms of sheer population, 2ch would become a national phenomenon, with over 10 million users per month and several hundred boards, even influencing the RL with tales like that of the Densha Otoko, which eventually got made into a movie. While 2ch diversified, 2chan remained Otaku-centered.
The western side of the story is shorter. While we can trace back Internet culture to MUD BBSs (Houston based board) back in the 80s, those directly responsible for what would become 4chan came to be on 1999, with Lowtax founding Something Awful. Under the slogan of "The Internet makes you stupid." Something Awful, as the name suggests, was a site dedicated to parodying and writing about all the bad and ugly things the post-bubble internet had to show. Lowtax and friends would make comedic posts around particular themes in the front page and had a personal forum for discussion of various topics. Sometimes they would organize contests, mainly Photoshop centered. Lowtax later charged an entry fee of 10 dollars – 10 bux, as it is colloquially known. Despite the blatantly elitist move, sites like SA were few and far between, and its ranks filled quickly. SA formed a culture around elitism, e-peen (ego, pride or attitude in the virtual world) size and a reputation for trolling and drama, gathering a skilled user-base of Photoshop wizards, coders, musicians and excessively ban happy mods, becoming a major source of Internet culture and popularizing lasting influences such as the image macro, the demotivational poster, Numa Numa (meme based on the dance single by the Moldovan pop trio O-Zone released in 2003), and the catchphrase All Your Base are Belong to Us (a broken English sentence from the opening cutscene of the 1991 video game Zero Wing).
Peers and contemporaries with legendary trolls such as Gamefaqs' LUE forums and the GNAA, whenever someone badmouthed the site one could expect an horde of goons to descend upon it, usually spamming it and tricking the site's users into clicking the Last Measure, a weaponized website that locked the user's browser and spammed the phrase "HEY EVERYONE, I'M LOOKING AT GAY PORNO!". This aggressive way of trolling is very reminiscent of the way Ayashii Worlders dealt with each other, however, the similarities end only with both sides' penchant for trolling.
Sometime between 18 April 2001 and 15 May 2001, Lowtax creates a sub forum called ADTRW, Anime Death Tentacle Rape Whorehouse, dedicated as the name suggests to anime and the Otaku fandom. ADTRW would develop its own jokes and culture, mainly a distinct hate for the sillier aspects of the fandom (The KAWAII DESU NEE, neko ears-wearing, awkward Otakus), acting like such being ground enough to be banned from the forums. On 2002 ADTRW would create a DC++ FTP called Raspberry Heaven, separating itself from SA's general FTP SADCHUB (Something Awful Direct Connect Hub). The name is derived from Azumanga Daioh's ending song. The FTP would have its own linked IRC hosted on MircX and later Pyoko IRC. By this time moot was already a member of both and could be seen on ADTRW and the IRC.
By 2003, the Otakus of SA would discover 2chan, becoming completely perplexed by the content filled, fast moving anonymous site. On ADTRW a 2chan appreciation thread would be created, and #raspberryheaven would come to be filled with 2chan links. Users interacted in a limited with the site, as much as their knowledge of Japanese let them. However, 2chan got in conflict with Korean communities, and they organized a massive raid. In order to protect itself, 2chan blocks all non-Japanese IPs, cutting ADTRW short from posting. To this day the Japanese only restriction still stands, and given Japanese nationalism, it will not be lifted anytime soon. Raspberry Heaven would be closed some years later as BitTorrent took over as the main method of warez and file sharing and Pyoko IRC closed its doors.
In March 2003, a Japanese teenager called RIR6 (Taichirou Kosugi) founds world2ch, a textboard hosted on US servers, with the aim of making a multi-language site for users of English and Japanese speakers. While the project became well-known on 2ch itself, the anonymous textboard format never really appealed to Westerners. Internet users in the West were used to accounts and the one-click smileys of conventional forums. Few saw the point of making time-consuming Shift-JIS art that was unable to view with the common ASCII encoding. Still, the board was a groundbreaking first in the export of the 2channel-style anonymous BBS. It's discovered by goons and other English speakers, and for a while posting between the two languages flourished. Many later influential names started out or at least passed by this site.
RIR6 had a rather basic understanding of English, and communication between the English speakers and the Japanese was very poor, but they managed. World2ch would have its own little culture between both worlds, importing 2ch memes like Giko-Neko and other SJIS. One particular meme stands above all: An English speaking Japanese user called Golgomois would come to the site demanding that the Americans remove their bases from Okinawa. The Americans on the site would come to outnumber the Japanese. They managed to convince RIR6 to open an imageboard and make various fixes. He makes two, these would be effectively the first Western imageboards, or rather the first Western populated ones.
RIR6 eventually lost interest and botched several fixes, making the site unnavigable, and eventually closed it on 2006. The userbase, most of its members already browsing both world2ch and 4chan, would flock to the latter.
These are all the sites and communities that preceded and influenced the creation of 4chan. By the end of September, moot jokingly registers 4chan.net, in order to have a personal email.