2 Wants To Know has told you how to spot skimmers on gas pumps and ATMs. Tug on the card reader. If it's loose, it's likely a skimmer. Or if the card reader covers the arrows below it - it's probably a skimmer.

But now you need to know about shimmers not to be confused with a skimmer.
They're showing up on ATMs.

A shimmer is a paper-thin, card-shaped device that's wedged inside of the card slot of an A-T-M or gas pump terminal. It has a microchip and flash storage that collects information from your credit or debit card.

The information is then used to create a phony magnetic strip version of your card. This only works on card readers that haven't been updated with chip technology. They're hard to detect since they're hidden inside the card reader.

So what can you do?

The Better Business Bureau suggests using the tap and go credit card feature instead of swiping.
Try Apple or Samsung pay. Use ATMs inside* banks or actually go to a teller at the bank. If you still want to use the ATM, look for any resistance when you insert your card.
if you feel some resistance, cancel the transaction.

Report anything suspicious to the ATM owner. Always keep an eye on your credit card statement.