- Domain Validation
Domain validated (DV) certificates are issued based on proof of control over a domain name. In most cases, that means sending a confirmation email to one of the approved email addresses. If the recipient approves (i.e., follows the link in the email), then the certificate is issued. If confirmation via email is not possible, then any other means of communication (e.g., phone or snail mail) and practical demonstration of control are allowed. A similar procedure is followed when issuing certificates for IP addresses.
- Organization validation
Organization validated (OV) certificates require identity and authenticity verification. It wasn’t until Baseline Requirements were adopted that the procedures for OV certificates were standardized. As a result, there was (and still is) a lot of inconsistency in how OV certificates were issued and how the relevant information was encoded in the certificate.
- Extended validation
Extended validation (EV) certificates also require identity and authenticity verification, but with very strict requirements. They were introduced to address the lack of consistency in OV certificates, so it’s no surprise that the validation procedures are extensively documented, leaving little room for inconsistencies.
Issuance of DV certificates is fully automated and can be very quick. The duration depends largely on how fast the confirmation email is answered. On the other end of the spectrum, it can take days or even weeks to obtain an EV certificate.
-- Ivan Ristić. Bulletproof SSL and TLS (Kindle Locations 1797-1809). Feisty Duck Limited.