Extended Validation (EV)
EV certificates offer the greatest deal of authentication and often times come packaged with other security products like malware scanners and vulnerability assessments. In order to get an EV certificate you have to undergo extensive vetting from the Certificate Authority issuing you the cert. This requires you to satisfy requirements for:
The upside is that EV certs unlock the green address bar in all browsers. This is an obvious visual indicator and your organization's name will be displayed prominently within it. It's impossible to fake a green address bar, so your clients or customers will have absolute assurance that you are who you say you are.
The downside is the price—but don't let that scare you. As we've already said, Extended Validation SSL/TLS certificates often come packaged with other security products. They also pay for themselves. Research shows that websites with EV certificates see a boost in conversions, meaning you see a considerable return on investment.