This device steals your pin number as well as your account number and access.
The above is just one example of such a device.
In order to avoid this pay attention to when you use an ATM. ATMS at airports and kiosks are the most likely sources. ATM's at banks and other places where there are security cameras are less likely to have problems with the skimmers.
When you use your ATM look very closely at the physical device that you put your card into. If there is anything suspicious, any part that looks fabricated post-factory do not use the maching and notify the bank if possible....
Pay attention to this. Avoiding the problem will save you hours in fees and frustration at trying to recoup your losses.