A skimmer is a type of malicious device or software designed to illegally capture sensitive payment information, such as credit or debit card data, during a legitimate transaction. Skimmers are often physically installed on ATMs, gas pumps, or point-of-sale terminals, where they secretly read and store card details from the magnetic stripe as customers swipe their cards. Some advanced skimmers may also include hidden cameras or overlays to capture PINs as they are entered. Cybercriminals use the stolen information to create counterfeit cards or commit fraud. Skimming attacks can be difficult to detect, making vigilance and regular monitoring of accounts essential for users.