Skimmers are illegal card readers attached to payment terminals. There are multiple types, including at other types of payment stations like ATMs, and they can be hard to detect. So, you should be cautious when filling at the pump. Often, stations will have attached security seals that you can check for tampering. If the seal is broken, you should tell the station and use a different pump. You can also check to see if the payment station looks different than the others around it. This could be another sign that a criminal has attached a skimmer. Unfortunately, you may not know your credit card information has been stolen until you get your statement. If you suspect your card has been compromised, at a gas pump, learn more about your options at our "What To Do If Your Identity Is Stolen" page.
For more tips on spotting this scam, visit Consumer.FTC.Gov.