Overview of Using a Wildcard SSL Certificate
A single Wildcard SSL certificate can secure multiple websites. Typically, a standard secure server SSL certificate is issued to a single FQDN. This means that the certificate can only be used on the exact domain to which it has been issued. The Wildcard SSL option, when activated, allows you to circumvent this restriction by receiving a Wildcard SSL Certificate issued to "*.domain.com". The (*) character replaces a fixed sub-domain with a variable one.