A security group is a collection of assets or grouping objects in VMware Cloud Director, such as virtual machines, organization virtual data center networks, or security tags.
Security groups can have dynamic membership criteria based on security tags, virtual machine name, virtual machine guest OS name, or virtual machine guest host name. For example, all virtual machines that have the security tag "web" will be automatically added to a specific security group destined for Web servers. After creating a security group, a security policy is applied to that group.