NIST definition of Community Cloud: The cloud infrastructure is provisioned for exclusive use by a specific community of consumers from organizations that have shared concerns (e.g., mission, security requirements, policy, and compliance considerations). It may be owned, managed, and operated by one or more of the organizations in the community, a third party, or some combination of them, and it may exist on or off premises.
Community clouds are intended to provide a complete cloud solution for specific business community. Business share infrastructure provided by the CSP (cloud-service providers) for software and development tools that are designed to meet community needs.
Salesforce.com is one of the best example of Community Cloud.
In addition, each business has its own private cloud space that is built to meet the security, privacy and compliance needs that are common in the community.
Community clouds are an attractive option for companies in the health, financial or legal domains that are subject to strict regulatory compliance.
Community Clouds are also well-suited to managing joint projects that benefit from sharing community-specific software applications or development platforms.
Goals of Community cloud: Community Clouds provides the capability to realize business processes in the cloud, and at the same time preserve a high-level security by means of hybrid deployment models. Community clouds allows the system and services to be accessible by a group of organizations. It shares the infrastructure between the several organizations from a specific community.
Summary: The Community Cloud allows system and services to be accessible by group of organizations. It shares the infrastructure between several organizations from a specific community. It may be managed internally or by the third-party.