Based on your financial expertise, provide your response or viewpoint on the given financial question or topic. The response format is open.

Would I ever need credit card if my debit card is issued by MasterCard/Visa?
You ask about the difference between credit and debit, but that may be because you're missing something important. Regardless of credit/debit, there is value in carrying two different cards associated with two different accounts. The reason is simply that because of loss, fraud, or your own mismanagement, or even the bank's technical error, any card can become unusable for some period of time. Exactly how long depends what happened, but just sending you a new card can easily take more than one business day, which might well be longer than you'd like to go without access to any funds. In that situation you would be glad of a credit card, and you would equally be glad of a second debit card on a separate account. So if your question is "I have one bank account with one debit card, and the only options I'm willing to contemplate are (a) do nothing or (b) take a credit card as well", then the answer is yes, take a credit card as well, regardless of the pros or cons of credit vs debit. Even if you only use the credit card in the event that you drop your debit card down a drain. So what you can now consider is the pros and cons of a credit card vs managing an additional bank account -- unless you seriously hate one or more of the cons of credit cards, the credit card is likely to win. My bank has given me a debit card on a cash savings account, which is a little scary, but would cover most emergencies if I didn't have a credit card too. Of course the interest rate is rubbish and I sometimes empty my savings account into a better investment, so I don't use it as backup, but I could. Your final question "can a merchant know if I give him number of debit or credit card" is already asked: Can merchants tell the difference between a credit card and embossed debit card? Yes they can, and yes there are a few things you can't (or might prefer not to) do with debit. The same could even be said of Visa vs. Mastercard, leading to the conclusion that if you have a Visa debit you should look for a Mastercard credit. But that seems to be less of an issue as time goes on and almost everywhere in Europe apparently takes both or neither. If you travel a lot outside the EU then you might want to be loaded down with every card under the sun, and three different kinds of cash, but you'd already know that without asking ;-)