Bank card numbers usually consist of 16 digits. The first six are to identify the issuing bank, and the last one is a check digit that results from putting the other digits through a special algorithm
. Protect looks for this pattern, so it can recognize when you enter your card number on a website. The card number itself is not sent anywhere.
As soon as Protect determines that you have entered in a card number, it checks whether the site you have entered it on is safe.
If the site uses the unsecure HTTP protocol, or Protect knows that it is fraudulent, you will see a warning and will be able to stop it from sending your card information.