Offer your thoughts or opinion on the input financial query or topic using your financial background.

What's the difference when asked for “debit or credit” by a store when using credit and debit cards?
When using a debit card in a "credit" way, you don't need to enter your PIN, which protects you from skimmers and similar nastiness. Also, assuming it's a Visa or Mastercard debit card, you now have access to all of the fraud protection and other things that you would get with a credit card. The downside for the merchant is that credit card transaction fees are typically higher than debit card transaction fees. I'm less familiar with using a credit card in a "debit" way, so don't have anything to offer on that part of your question.