Watch out for executable files, such as '.exe', '.bat', '.pif', and '.scr'. If you download one of these you are, potentially, opening yourself up to anything on that file once you activate it. Try scanning it with a virus checker or any other software that is like it-just to be on the safe side.
card verification value (CVV) Card verification value (CVV) is a combination of features used in credit, debit and automated teller machine (ATM) cards for the purpose of establishing the owner's identity and minimizing the risk of fraud. The CVV is also known as the card verification code (CVC) or card security code (CSC).
Tarek Sanyoura's answer is on target so nothing in this post is intended to detract from his. From a purely technical perspective, or perhaps just one focused on semantics, CVV (i.e. Card Verification Value) and CVV2 are the abbreviations used uniquely for the security codes present on cards bearing the Visa brand.