Whenever someone who doesn't seem that interested asks me about play by post, I just quickly tell them that it's a form of collaborative writing. That description is entirely true, if terse. When you enter into a play by post board, the most important thing you are doing is joining a group effort to create a story that none of the component members would have come up with alone; a whole greater than its parts.

In most play by post forums, each person has a small number of personal characters followed by his or her part of the story. In some cases, these characters "level up" through continued use as a way to encourage players to vie for quality in their work. In other cases, the forum is much more relaxed and forgoes such a system. (Quichetopia is an example of the latter.) By having each player have sole providence over a particular character, the story has an easier time keeping it's characters consistent and distinct from each other. It also prevents any one character from stealing the focus.

In play by post forums, the story is played out as players post about what is happening to their characters. Pretty straight forward, no? Depending on the forum's customs and the players' preferences, posts can range from being a sentence or two each to being many paragraphs long. The key thing is that players take turn posting, building their stories a little bit at a time instead of all at once.

One feature common to most play by post systems is that absolutely nothing can happen directly to anybody's character unless they allow it. When somebody tries to circumvent that rule by declaring that something has happened to a character that is not their own, it is called "bunnying." Most forums have harsh penalties for players who "bunny" other players' characters.