Online fraudsters are increasingly turning to phishing in an attempt to steal your personal data. It's a simple idea: they produce a realistic fake of a site like Paypal, for instance, then lure you to it, get you to log in, and steal your user name and password. Your account is duly emptied, a few minutes later.
It's a good idea to check the credentials of the web sites that you use, then, and Comodo Verification Engine tries to help in a few different ways.
The simplest addition is a pop-up padlock graphic, that displays every time you visit an SSL-protected site (any URL beginning with https) and shows who's registered its certificate. You should already see a padlock in the browser address bar, of course, but that has been faked in the past by a little graphical trickery, so this does at least confirm you're at a secure site. (As long as you're using IE or Firefox, anyway - the program doesn't work with Chrome, Opera or Safari.)
Comodo Verification Engine additionally checks that website login boxes are legitimate, and really connect to the company you're expecting. And it looks at both the domain name and IP address of the site you're visiting, to confirm that (for instance) a malware-tweaked HOSTS file isn't redirecting your web traffic to a phishing site.
The program is also supposed to identify real sites by simply hovering your mouse cursor over their logo: in a second or two, you should see a green box drawn around the browser window to confirm it's genuine. Unfortunately this only works with sites that have registered with Comodo, and in our experience there's not enough to make it really useful yet (it worked with Paypal and Ebay.com, for instance, but not Amazon or ebay.co.uk). Hopefully Comodo will work to sign up more of the big sites soon.