If you've made it to this article, you're probably wondering what an "otaku" is or you already know and want to know some more about the origin of "otaku." In either case, you've definitely made it to a good starting place to get your information.
The word "otaku" was (and still is) used as a way to say "another's house" in Japanese, but has recently taken on a different twist that changes its meaning to "geek" or "nerd" when used to describe a person. Although it can apply to nearly anyone that has an intense interest in a particular hobby (let's say a person that really loves to collect rocks and practically has a dedicated shrine to their collection in their house), the word "otaku" is generally applied to those that are deeply entrenched in anime and manga culture. This is especially true outside of Japan's borders where "otaku" is usually only known as a person that loves anime and manga.
The difference between how the Japanese use the term "otaku" and how others use the word only captures a portion of the picture though. When comparing the two usages, the Japanese usage of "otaku" has more negative connotations than, say, an American's usage of the word. This is because of the specific histories that are associated with otaku in Japan where negative events and/or tragedies were blamed on the person's interest in anime or manga. This has resulted in the Japanese society frowning about anything associated with anime or manga at various points within the last few decades.
On the other hand, being an otaku outside of Japan is looked upon somewhat differently. If you're an otaku in a different country, then the term "otaku" does not have as much of a stigma attached to it because the people around you wouldn't know the specific histories attached to the word "otaku" like it does in its native country of Japan. Because of that, it's generally a term that's used within the fandom to refer to themselves or those similar to them (where "otaku" is still usually used when the person in question watches anime as each season comes out, reads manga as each chapter is released, collects figurines, buys DVDs of their favorite anime series, and has posters of various anime or manga characters). And even then, there's a divide as to whether or not a fan in a different country will label themselves as "otaku." This is because anime and manga fans that are aware of the negative connotations of "otaku" in Japan are wary of labeling themselves as such. Even with oceans separating them from Japan, there are many fans that don't want others to think that they are associated with the people who committed crimes and just happened to have an interest in anime and manga.
Regardless of the slight negative connotations of the word, there are still numerous anime and manga fans that will proudly call themselves "otaku" (at least outside of Japan). They're not afraid to talk in public about the latest episode of Bleach or Naruto that came out, or ask if someone has downloaded any anime from the current season so that they can watch it. They'll sketch doodles of anime and manga style and post them on sites such as deviantART. Some will even attempt to make their own anime or manga through the use of programs such as Anime Studio or Manga Studio. It's a fandom that's close-knit and allows anyone to make friends simply by asking if they enjoy a certain show.
Chiaki Shiraishi is a lover of travel and exploring new cultures. After visiting Japan, she couldn't resist the pop culture that was so prominent in the capital of Tokyo. She found the differences in how otaku are viewed in Japan versus her home country (America) striking and asked her traveling companions from other countries what it was like in their home countries. This inspired her to delve more into the subject to find out more, resulting in this article about anime and manga fans.
Chiaki Shiraishi also writes a couple different blogs. One that explores various sites and items/services found on the web ( http://explorenzie.blogspot.com/ ) and another that will portray the life of two friends through 4-panel comics and commentary ( http://butoku2011.blogspot.com/ ).