First, it means that all my personal information that I am sending to the online merchant is encrypted. People on servers in between might be able to intercept our communication, but only the merchant has the "key" to unscramble what I send. That means that my credit card number and my shoe size are safe.
Second, it means that the merchant has an Extended Validation SSL Certificate. SSL certificates are the documents that contain the "keys" to unscramble encrypted text. It's harder to get an Extended Validation SSL certificate than a regular Domain Validated Certificate and the Extended Validation certificate tells me about its owner's legal organization.When I shop, whether in person or online, I like to know as much as I can about where my money's going.
Merchants who use Extended Validation certificates from any company will show the green browser bar. Often you will not see it until you get into a section of the website that needs to be encrypted, such as when you need to sign in.)
Merchants who buy their Extended Validation certificate from Comodo can also show this logo on their sites. If you use Comodo freeware, please consider supporting the merchants who buy Comodo certificates.