A single Wildcard SSL certificate can secure multiple websites that use subdomains (that is, variations of the same domain name like subdomain.domain.com).
Typically, a standard secure server SSL certificate is issued to a single Fully Qualified Domain Name only, which means it can only be used on the exact domain (including subdomain) for which it has been issued. For example:
- A certificate that secures domain.com will not secure subdomain.domain.com
- A certificate that secures subdomain.domain.com will not secure domain.com
With the Wildcard SSL option activated, you easily get around this restriction by receiving a Wildcard SSL certificate issued to *.domain.com. The * character replaces a fixed subdomain with a variable one. This means you can secure any subdomain, even one you create after the SSL certificate is installed.