A hacker has many ways to gain a credit card number from an innocent user. The most common one is known as phishing. In this technique, the hacker poses as an officer within an organization, let's say VISA. The hacker sends to a group of email accounts an alert, instructing the receiver to follow determined set of instructions before his credit card is cancelled. If the user is not aware of this kind of fraud, he will insert his credit card number, his name and expiration date without knowing he is going to be a victim of an online crime. Another way for hacking credit card numbers is through a website. The hacker only needs to hack the systems of an online retailer, let's say, Costco, and search for the database where the retailer stores the information of all of the users who have made recent transactions. The third way is through the online process of buying.
