What is a Certificate Authority?

SSL certificate serves as a credential in the online world. Each SSL certificate uniquely identifies a specific domain (such as eDomain.co.il) and a web server. Trust of a credential depends on confidence in the organization that issued it. Certificate authorities have a variety of methods to verify information provided by individuals or organizations. Established certificate authorities, such as Thawte, GeoTrust, Veisign or Rapid SSL are well known and trusted by browser vendors.

Authentication means that a trusted third party, as mentioned, has verified the identification information contained in your SSL certificate, assuring customers that your site is actually your site.
Concerns about fraud and identity theft have made users more hesitant to share personal information with unfamiliar web sites.