These terms might be useful for those of you who are unfamiliar with non-computer-based role-playing, or even "yarns" in general. If there's any term you're unfamiliar with that you feel belongs on this list, please e-mail me and I'll add it.
Useful Terms:
Character: A created person a "player" pretends to be (or, if you prefer, writes for) during a yarn.
GM: Short for "game master"--the person in charge of the yarn, the person to talk to if you're confused, need help, have problems, etc., or if you have any story ideas. Also the person who steers the story.
Player: A human participant in a yarn (as distinguished from his/her character(s)). In short, if you're involved, you are a player.
Yarn: An online text-based roleplay with two or more "players," each of whom has at least one "character." Conversation and interaction is stressed; fighting and chance-based encounters are greatly downplayed.