"Clusters are geographic concentrations of interconnected companies, specialized suppliers, service providers, and associated institutions in a particular field that are present in a nation or region. Clusters arise because they increase the productivity with which companies can compete." A cluster is not an industry or trade association that a business must join to become a member; rather businesses are part of a cluster based on their location and connectedness to others in the supply chain of the particular field.
 Institute for Strategy and Competitiveness, Clusters and Cluster Development, Harvard Business School.
"The development and upgrading of clusters is an important agenda for governments, companies, and other institutions. Cluster development initiatives are an important new direction in economic policy, building on earlier efforts in macroeconomic stabilization, privatization, market opening, and reducing the costs of doing business."
[ Source: Institute for Strategy and Competitiveness ]