Chao designed a categorisation scheme for online communities in 1999.

S/he based this on McMillan and Chavis’s definition, which suggests s/he felt that online communities are like offline communities. I wonder if that’s the case. Is anything online the same as it is offline? Anyway Chao looks at the four categories like this:

Membership – self-disclosure statement, acknowledging others’ membership, the paying of dues in terms of time and energy, references to the boundaries of the community, completing forms needed to become a member.
This suggests active, posting membership. Are lurkers not part of the community? How often would you have to post in this way to maintain your community membership?

Influence – refer to norms, rules or other orders, attempting to influence others, being influenced by others, identifying and trusting some authority.
Mmm, yes, OK

Fulfilment of individual needs: seeking common ground, expressing a personal needed, acknowledging receipt of needed info, voicing criticisms, suggestions or differences of opinion.
I think I’m least happy with this because surely there are communities you belong to by default and others you are a member because you are required to be.

Sharing events and emotional experiences – stories of the past, using special symbols / language
I suppose you could also include use of hotlinks in here. Maybe also threading. Evidence that users have looked at the archive?