A Wildcard SSL [Certificates] helps in achieving SSL encryption on multiple sub-domains with the help of a single certificate as long as the sub domains are on one same physical server, share the same second-level domain name and are under the control of a single organization. 

For example, one wildcard certificate {{{*.yourdomain.com}}} would be able to secure the following websites :
* www.yourdomain.com
* secure.yourdomain.com
* product.yourdomain.com
* info.yourdomain.com
* download.yourdomain.com
* anything.yourdomain.com

However, the following will not work:
* foo.info.yourdomain.com
* bar.secure.yourdomain.com

These sites would require a separate certificate for each sub-domain:
* *.info.yourdomain.com
* *.secure.yourdomain.com

!!Older Browsers
'Older' browsers don't recognize wildcard certificates and report a name conflict between the domain and the certificate. 
* IE5.5 is ok, 
* and I think IE5.0sp2 is ok. 
* Prior versions of IE will have problems and I'm not sure
* Netscape - 7 onwards is definitely ok, and I think 6 is as well.
* Not sure about 4.7.!! More Information
There might be more information for this subject on one of the following:
[{ReferringPagesPlugin before='*' after='\n' }]