If you are selling online then you should be familiar with an SSL certificate. But what about a UCC SSL Certificate?
Unified Communications Certificates (UCC) are SSL Certificates that secure multiple domains and multiple hostnames within a domain. They allow you to secure a primary domain, and up to 99 additional Subject Alternative Names, in a single certificate. UCCertificates are ideal for Microsoft® Exchange Server 2007, Exchange Server 2010, and Microsoft Live® Communications Server.
UC Certificates are compatible with shared hosting however, the site seal and certificate "Issued To" will only list the primary domain. Please note that any secondary hosting accounts will be listed in the certificate as well, so if you do not want sites to appear 'connected' to each other, you should not use this type of certificate.