“Not all groups are the same” is a total understatement.  Group owners can be very paranoid about the operation of their group, how it is configured, how it is used, and this covers aspects that are technically controllable and those that are only controlled via softer policies.

So for example, one can, as an owner, enforce most group technologies such that any new member applications have to be approved by you.  As an alternative, as an owner one could instead run a group where no such approval is necessary, excepting that the group is largely hidden from Internet searches (for example the Yahoo or Google Groups directory) and that new members are obtained via an invitation process.  As a further nuance that “invitation” could itself be distributed on the Internet for anyone, or specific target groups to access and use.
In operational matters also not all groups are identical.  For example some groups operate more as an announcement tool.  This is typically true of what may be considered as high-volume groups.  (By high-volume I mean the number of posts per day, month etc and to put some colour on that anything above say 100 posts per day should be considered as an initial ball-park for high volume, but we may come back to that subject later.)  An announcement group is one where posts are made but not generally discussed.  This may include groups where advertisements for items for sale (or for free) are made, or where perhaps press releases are made.

In contrast a discussion group truly makes use of the group as a debating forum.  This is when people perhaps openly ask a question, such as “does anyone know what happened last Wednesday at the court appearance of Joe Bloggs?”  Here there is an open invitation not only for people to comment on the facts at hand but also express opinions.  Further to that people often disagree about what is a fact and what is an opinion and so such debate can often escalate, even emotionally.

Welcome to my Groups commentary. The world of groups is an ever expanding phenomenon.  I have not yet found a decent summary about the virtual communities, how they operate, why they exist and so on and so forth.  That is in part what I hope that this Groups Commentary will become. Over time I hope it will be seen as a resource for those interested in the subject, perhaps as background research, perhaps as a way of finding good resources on the subject, perhaps as a way for prospective owners to improve their skills or even justify the immense time they put into groups – for free.

Whatever this commentary becomes I hope it is not stagnant in its thinking.