How does debit / credit card skimming work?

Once the fraudsters have captured the magnetic stripe information and corresponding PINs, then they create a duplicate ATM card that looks just like a debit / credit card, for use at ATMs /retail outlets etc. The cards appear to be legitimate, and retailers have no way to know fakeness of those cards. Fraudsters wait for a few days or a few months with the fake card. Then they go on a spending spree or find an ATM to withdraw cash. This usually happens on weekends or late at night when financial institutions are closed and account holders are not monitoring their accounts.