Virtual Organizations (VO):

A VO enables a collaborative environment where communities of researchers, practitioners, policy-makers, and others come together to share knowledge and information, analyze data and solve problems through sharing of resources. Basically a VO is a grouping of users (consumers of grid-services) and resource-sites (provider of grid-services). Example of VOs can be Application Communities like Bio-informatics, Astro-Physics, Atmospheric Science etc.