Your trading partner may require that you send them your certificate before allowing you to connect to their SSL-enabled server. Depending on your trading partner’s authentication requirements, there are three different approaches in which a certificate can be signed and issued:
You can issue your own certificate. Also known as a Self-Signed certificate. This is the lowest level of trust.
Your trading partner can issue your certificate.
A Certificate Authority (CA) can issue your certificate. This is the highest level of trust.
A certificate authority (CA) is a trusted organization that issues Public key certificates. The job of a CA is very similar to that of a notary public. You must provide proof identity to the CA in order to obtain a certificate from the CA. Once the CA is confident that you represent the organization that you say you represent, then the CA will sign the certificate attesting to the validity of the information contained within the certificate. A CA will generally charge a fee for this service. Examples of popular CA's are VeriSign™, Entrust™ and Equifax™.