ATM is the acronym of automated teller machine or automatic teller machine. It is a computerized telecommunications device that enables the clients of a financial institution to perform financial transactions without the need for a cashier, human clerk or bank teller.
ATMs are available in the historical center of Lucca close to banks (and, you know, we have a lot of banks in Lucca!), in supermarkets or in shopping centers. Of course you have to check if they are dealing with the financial circuit of your card and, before leaving home, ask your bank if you have to pay fees when using ATM service abroad. For Mastercard users I have found this useful Mastercard ATM locator.
Credit cards are usually welcome in shops but if you have to pay small amounts (newspapers, breakfast, a good espresso..) cash is required.