There are 2 types of Debit Cards which are issued by VISA as given below.
VISA Debit Cards: When you use these debit cards for shopping at merchant outlets you do not require a 4 digit Debit Card PIN to be used. Just one swipe, and the money leaves your account and your shopping has been paid for.
VISA Electron Debit Cards: When you use Visa Electron Debit Cards you will need to use the 4 Digit PIN for shopping as well as ATM Transactions, when you swipe a card at the merchant outlet, the person at the billing counter will give you a keypad on which you will enter a 4 digit PIN after which your transaction will get authorised. There is an additional security for shopping transactions
The bank you bank with, usually takes the call if the customers are to be issued VISA Debit Cards or VISA Electron Debit Cards (or Master Card Debit Cards or Maestro Debit Cards).
If your wallet has got robbed and you have 1 VISA Debit Card, 1 VISA Credit Card and 1 VISA Electron Debit Card the risk you are exposed to due to each of them are as follows.
(1) The robber can use your VISA Debit Card for shopping and any money that he spends on it is never coming back to you …… no matter what you do, as that money has already left your account
(2) The robber cannot use your VISA Electron Debit Card as there is a 4 digit PIN protecting it and hence your money in the Account is safe
(3) The robber can use your Credit Card, however you can raise a chargeback with you Credit Card company and at the end of the day refuse to pay the money back (at the risk of ruining your credit record)
So the point to be remembered is that, if your bank has issued you a VISA or MasterCard Debit Card and you lose the same the risk is considerable as there is NO PIN based protection for shopping transactions, however if you have a VISA Electron Debit Card you are secure.
So please take care before going with VISA as these are the finer points VISA does not tell you about.