Etiquette forms the basis of conduct which is strongly recommended in a social circle or community, and often required by others in more official circles. These formal rules develop in many social arenas. Etiquette is like a code for behaviour that can be observed by others.
Etiquette is about communicating in such a manner as to give a good impression to other members of the community. It can be used to advocate a preferred opinion by attempting to create a perceived identity which is favoured.
This is a list of wiki topics dealing with online etiquette in several media.
TakeDown.NET -> “Etiquette”