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.