This article lists down some basic information about the different terms used throughout the Ore no Imouto ga Konnani Kawaii Wake ga Nai light novel series and its manga adaptation.
A BBS or bulletin board system is a popular term used for online forums and imageboards. The term itself originated from a similar form of communication way before the advancement of HTML and websites, and it was eventually used to describe places where people can discuss similar interests online.
Eroge (エロゲ, from エロゲーム, "erotic game") are games which often depict mature situations and instances of sexual intercourse. Because of the nature of this kind of game, they are often labeled as R-18 or restricted to 18-year-old buyers. In the present, eroge are usually played using a personal computer.
Fujoshi (腐女子, lit. "corrupted girl") are female fans of anime or manga who are enthusiastic with depictions of male eroticism.
An ofukai (オフ会, lit. "offline meeting") is an event often held by online communities for its members to meet and greet other members in person. The term is derived from the English word "offline" and the Japanese word "kai" which means meeting.
The term otaku (オタク, originally 御宅, lit. "one's house") is the general term used for avid fans of anime and manga, but can be used for hobbyists who partake in obsessive interests.
More popularly known in the real world as ASCII Media Works, this company publishes magazines and novels, including light novels. The Ore no Imouto light novels is published under the Dengeki Bunko imprint.
Someone with a sister complex is overly attatched to their sister. In strict terms, it does not have to be romantic or sexual but can be suggestive of that nature.
A social networking service (or social networking site) is a website that allows users to publish content and interact with other users with similar interests.