At this point, nearly every online rpg forum or newsgroup has seen has seen the concept of a Threefold put forth. At its most basic, A Threefold model states that many of the core ideas driving role-playing campaigns can be expressed in three terms, say for example Simulation, Drama, and Game.
To my knowledge the first of these appeared in rec.games.frp.advocacy in and around the summer of 1997 and is detailed in the r.g.f.a FAQ. This model was mostly concerned with how decisions are arrived at rather than direct definitions of game systems. A simple example of that model: does a GM place a villain according to where he’d actually be (Simulation), where needs of good drama requires him to be (Drama), or in a location that he thinks would make for the most interesting test of skill for the players (Game).
The original idea was to explain in a simple way that people do different (or even the same) things in rpgs for different reasons, a nice attempt to avoid the “You’re wrong, I’m right” flame ridden threads of the time.
In common Internet fashion, the idea spread from there to other locations and has now appeared in nearly every major general rpg site on the internet, often in very different forms.
In every place a Threefold has appeared, heated debate (and flame wars) quickly broke out. Almost to the extent that there were (and are) times when other meaningful traffic was drowned out. The arguments have gone on for so long, and with such passion, that some regulars in each group are likely to treat any critic of their model as an troll. It does however remain a good way to start a long and involved thread at the drop of a hat, assuming such things suit you.
For some reason, I get dragged into those debates. While not a passionate proponent or opponent of the threefold concept, I do feel that that there are major problems with the original model, as well as some interesting ideas. Rather than repeat myself all the time, I thought I’d make my viewpoint clear here. That way I can tell people to go read the website and hopefully move on to more interesting discussions or at least something new in the age-old Threefold debates. There are a number of subtopics in this subject, so I've split them out in order to be able to direct people to those sections in question at the time.