The Secure Socket Layer (SSL) protocol was created to ensure secure transactions between web servers and browsers and can be identified by checking your browser’s address bar for the presence of the https:// protocol and other indicators (like a lock or a key in the browser’s status bar) that ensure the data is being encrypted. The protocol uses a third party, a Certificate Authority (CA), to identify one end or both end of the transactions.
A certificate authority or certification authority (CA) is an entity that issues digital certificates. The digital certificate certifies the ownership of a public key by the named subject of the certificate. This allows others (relying parties) to rely upon signatures or assertions made by the private key that corresponds to the public key that is certified. In this model of trust relationships, a CA is a trusted third party that is trusted by both the subject (owner) of the certificate and the party relying upon the certificate.