What is difference beween a debit card and a credit card?

A debit card is issued by your bank, and when you use it, funds are withdrawn from your bank account thus reducing the money you have the bank. It's like writing a check.

When you use a credit card you are, in effect, borrowing money from some company or institution to pay for your purchase and must pay this money back at some time in the future. But, the amount of money you have in the bank is not affected.