Extended validated server certificates may be shown as a green address. They are expected whe the transactions you do with the site is extra valuable, eg banking and health businesses.
An EV Certificate is a quite new type of certificate that is designed to prevent phishing attacks better than normal SSL certificates An SSL Certificate Provider has to do some extensive validation to give you one including:
- Verifying that your organization is legally registered and active
- Verifying the address and phone number of your organization
- Verifying that your organization has exclusive right to use the domain specified in the EV Certificate
- Verifying that the person ordering the certificate has been authorized by the organization
- Verifying that your organization is not on any government blacklists
It is even better if the Certificate Provider is one that can be trusted.