Some organizations need SSL simply for confidentiality, e.g. encryption.
Some organizations wish to use SSL to enhance trust in their security and identity, e.g. they want to show customers they have been vetted and are a legitimate organization.
There are several types of SSL Certificates:
Domain Validation Certificates
Domain Validation (DV) SSL Certificates: where the Certificate Authority (CA) checks the right of the applicant to use a specific domain name. No company identity information is vetted and no information is displayed other than encryption information within the secure site.
Organization Validation Certificates
Organization Validation (OV) SSL Certificates: where the CA checks the right of the applicant to use a specific domain name PLUS it conducts some vetting of the organization. Additional vetted company information is displayed to customers when clicking on the Secure Site Seal, giving enhanced visibility in who is behind the site and associated enhanced trust.
Extended Validation Certificates
Extended Validation (EV) SSL Certificates: where the CA checks the right of the applicant to use a specific domain name PLUS it conducts a THOROUGH vetting of the organization. The issuance process of EV SSL Certificates is strictly defined in the EV Guidelines, as formally ratified by the CA/Browser forum in 2007, that specify all the steps required for a CA before issuing a certificate, and includes:
Verifying the legal, physical and operational existence of the entity
Verifying that the identity of the entity matches official records
Verifying that the entity has exclusive right to use the domain specified in the EV SSL Certificate
Verifying that the entity has properly authorized the issuance of the EV SSL Certificate
EV SSL Certificates are available for all types of businesses, including government entities and both incorporated and unincorporated businesses. A second set of guidelines, the EV Audit Guidelines, specify the criteria under which a CA needs to be successfully audited before issuing EV SSL Certificates. The audits are repeated yearly to ensure the integrity of the issuance process.
EV SSL are designed to provide a higher standard of assurance for visitors to authenticate the business behind the domain. Only EV SSL certificate can display your company or organization name by clicking padlock in the address bar, which reassures website visitors that they are interacting with a verified business on a secured domain.
Wildcard SSL Certificates
Wildcard SSL Certificates enable SSL encryption on unlimited subdomains using a single certificate (e.g. *.domain.com).
Multi-Domain Certificates
Multi domain certificates (MDC) aka Subject Alternative Name (SAN) make it possible to secure multiple domains with a single certificate. You can mix all your different second level domains (e.g.: domain.com, www.domain.com, domain.net, and otherdomain.com).
