  Many benefits of online communities---such as obtaining new information,
opportunities, and social connections---increase with size. Thus, a
``successful'' online community often evokes an image of hundreds of thousands
of users, and practitioners and researchers alike have sought to devise methods
to achieve growth and thereby, success. On the other hand, small online
communities exist in droves and many persist in their smallness over time.
Turning to the highly popular discussion website Reddit, which is made up of
hundreds of thousands of communities, we conducted a qualitative interview
study examining how and why people participate in these persistently small
communities, in order to understand why these communities exist when popular
approaches would assume them to be failures. Drawing from twenty interviews,
this paper makes several contributions: we describe how small communities
provide unique informational and interactional spaces for participants, who are
drawn by the hyperspecific aspects of the community; we find that small
communities do not promote strong dyadic interpersonal relationships but rather
promote group-based identity; and we highlight how participation in small
communities is part of a broader, ongoing strategy to curate participants'
online experience. We argue that online communities can be seen as nested
niches: parts of an embedded, complex, symbiotic socio-informational ecosystem.
We suggest ways that social computing research could benefit from more
deliberate considerations of interdependence between diverse scales of online
community sizes.
