Is a group of people a community if its members don't know they're part of it? I don't think so, but some recent blog posts have confused community with something else. Before we redefine all of the useful distinction out of yet another buzzword, let's think about what makes a community. After all, your community engagement strategy requires a community to engage.
What a community is
Community is a nice-sounding word that threatens to become just another euphemism. Activists use it to describe entire populations, usually based on some attribute that gives them minority status. Politicians refer to "the community of nations," which is either all of the world's governments or the entire world population (clarity seems not to be the point). Community has come a long way since its local roots.
Now, marketers are using community to describe groups they'd like to reach. The references that inspired this post listed "communities" that were really market segments, such as teenage girls or white-collar professionals. While these examples can be useful segments, they're missing the essential elements of community:
Members not only know that they're a part of the group, they think of it as a community (but they might choose a different word to describe it). Membership in a formal organization is a big hint here, but not a requirement.
Communities know who is not a part of the community, too.
Members of communities have social connections with each other. They recognize each other as members of the same community.
Without communication, there's no community, and old communities fall apart. But communication alone doesn't necessarily lead to community.
Community members usually provide some level of support to each other.
Communities form for many reasons. Some reasons—common interests, careers, industries, demographics, geography—map nicely to segments that marketers find interesting. But members of market segments—whether defined by demographics, psychographics, purchase patterns or interests—don't form communities just because marketers want to try community strategies to reach them.
If your goal is to apply a community-oriented strategy to reach a particular market segment, your choices are to connect with an existing community or try to create one. And please, don't call a segment a community if there isn't one there.