I get asked this a lot.
A community manager manages a specific community and/or platform for an organization. He or she may wear many hats including brand champion and engagement specialist for that community. The community manager may be tasked to create and manage content. In a nutshell, a community manager uses online networks to be the voice of the company to the community and the voice of the community to the company.
Generally, a very digital-savvy employee, her or she is responsible for all communications, PR, social media, events, and out bound messages.
This role can be in-house or outsourced but the job requires someone who is intimate with the brand and has the authority to make decisions.
John Bradley Jackson
The BirdDog Group