What is the difference between domain validation, business validation and extended validation?

Domain validation: Domain validated certificates include your domain name in the certificate (not your business or organization name). These certificates are cheaper and usually issued in minutes as the Certificate authority validates your domain by looking at the WHOIS information for your domain. However, these certificates provide less assurance to customers.

Full business validation: In business validation certificates the certificate authority verifies your ownership of the domain name and business registration information (you will be asked to submit a few documents) before issuing the certificate. Both of these items are listed on the certificate as well. Because it requires manual validation of your business, these certificates can take an hour to a few days to be issued. They provide higher assurance to your users.

Extended Validation: An EV certificate is designed to prevent phishing attacks and provides the highest level of assurance to your customers. It requires extended validation of your business and authorization to order the certificate (you will be asked to submit a few documents). It can take a few days or few weeks for a certificate authority to issue an EV certificate for a domain. But, it provides maximum assurance to customers by making the address bar of the customer's browser turn green when they visit your site.

Certificate Transparency for certificates

In order to improve the security of Extended Validation (EV) certificates, Google Chrome intends to require Certificate Transparency (CT) for all EV certificates issued after 1 Jan 2015.

Here are the main points to take to consideration:

- All EV certificates (including already issued certificates) with validity periods beyond Jan 2015 should support CT.

- On or after (depending on Chrome release schedule) 1 Feb 2015 Chrome for desktop platforms will cease to show the EV indicator (green bar) for certificates that do not support CT.

As for Certificate Authorities, Comodo has already built and prepared the infrastructure to support CT for all EV certificates they issue. They have begun including the necessary extensions into all new EV certificates requested from 15th December 2014.

Additionally, since October, 2017 all Domain and Organization SSL certificates should also support CT to be trusted in Google Chrome browser.