I would define the community of library-land as including all peoples, regardless of geographic location, who are interested in creating, storing, sharing, and/or using information. I realize this is an extremely broad definition, but that’s what librarians specialize in – being a “jack of all trades” when it comes to connecting people to their information needs.
What makes this community sustainable is, in part, the librarian’s ability and willingness to connect people with their information needs. Much of a librarian’s ability is learned through graduate education, continuing education opportunities, and experience of being on the job. Willingness is an aspect of library-land sustainability that is just as important as ability but relies on individuals’ values to determine the extent to which it is practiced on a case-by-case basis.
The financial and ideological support of one’s local community (geographic or institutional) is also vital for the library community to remain sustainable. Without the budgetary supports that allow librarians to help people create, store, share, or use information, we are not able to maintain our community. Equally, the ideological buy-in from one’s local community allows a librarian to engage in methods and with people in ways that continue to sustain the library community.