Shoko Nakagawa, an otaku idol, teaches otaku definition, and the various types of otaku. The video is subbed (not by me of course), and split into two parts.
Summary, for those unable to see the video:
in Japan the word otaku (オタク) refers to more negative connotation (“nerd”), thus the word wotaku (ヲタク) is used. However, otaku and wotaku are used interchangeably, depending on the mood and personal style of the poster. In Japan the word wotaku (ヲタク) represents people whose obssesively passionate about their hobby which concentrates strongly on a subculture primarily interested in stuff like anime, manga, etc.
There are 12 category main types of otaku, which are:
Anime ota. The largest otaku sub-type. These people like to watch and collect japanese anime.
Manga ota. These are people who read and collect manga (Japanese comic), some of Manga otaku also write/draw their own Manga.
Seiyuu ota. Seiyuu is anime voice actor/actress, these type of otaku can recognise the voice of the seiyuu just by hearing the voice. They also purchase seiyuu song albums and follow seiyuu events.
Cosplay ota. Person who dresses like character in anime/game. Cosplay begun in the year of 1976 when a participant in comiket dresed as Umi no triton. in 1990s cosplay exploded and became huge things thanks to the anime culture (Evangelion mainly) in Japan. Nowadays, the practice of cosplay in one’s own home and taking photo of yourself have become prevalent.
Figure ota. People who collect figures or plastic models. There are two types of them, first one is the people who collect expensive figure or resins, and the second one is gachapon/gashapon collector (gachapon is small trading figurines with random content, where in japan you can buy it from machine).
Maid ota. Also known as meidosuki (which means maid love). These otas love people who dress and acts as maid. Some people may ask, why do people like maid? the answer is because the desire of power, “Ah, it’s a maid that will do all whatever I say”
Idol ota. Opposition of anime ota. Idol otas are interested in real human (in japan this is called 3D) instead of animation/drawing (this term is called 2D). These otakus comes idol events, collect idol trading cards and photo books.
Game ota. Person who likes to play and collect game. In Japan, most of these type of otaku can be seen hanging around in arcade games, and majority of them are good in fighting games.
Gunji ota. These are people who really into military, weapons, military vehicles, etc. Gundam lovers are considered as gunji otaku.
Eroge ota. Eroge means erotic game. This kind of people like to play erotic game (hentai game). They also collect ero game characters merchandises.
Tetsudou ota. Railroad/Train otaku. There are two types, noritetsu: person who love travelling by trains, and toritetsu: person who love to take photos of them. Seems like not many of this otaku sub type found outside Japan.
Pasocon ota. Pasocon means personal computer, these otas are the personal computer geeks. Usually these otakus have their PC equipped with the latest and most advance computer parts.
Some Otaku Vocabularies
Tsundere, which means someone who act cold but actually care for that person. For example: a tsundere girl will say “Of course I didn’t make it for you!” while giving him a bentou (lunch box).
Boy’s Love / Yaoi, Manga or Anime genre which focuses on male on male relationship.
Fujoshi, ( 腐女子 literal translation is “rotten girl”), term for female fans of Yaoi manga or anime. There are several others (but not common) name for female Yaoi fans, which are: kifujin ( 貴腐人 “rotten woman”) for older fujoshi females, and ochoufujin ( お蝶夫人 “disgraceful super rotten woman”).
Moe, ( 萌え, pronounced mo’e). This word describes interesting/lovable aspect of female anime character (normally girl character). Example of moe traits: tsundere, clumsy, silent, eye glasses, small cute girl, etc.
Bonus! After all these lesson, best is to cool your head by watching the cute Otaku Idol Shoko-tan sings (the song title is Strawberry Melody)
しょこたん、すきすきです！Shoko-tan, suki suki desu! (Shoko-tan, I love you!) She is definitely Otaku Idol!
[added 9th May 2007]
[Updated 17th Dec 2007]
Changed some of the wording.