In cybersecurity, harmonics refer to signal frequencies that are integer multiples of a fundamental frequency, often produced unintentionally by digital circuits or electronic devices. These harmonics can be exploited to generate higher radio frequencies, which may inadvertently leak sensitive information through electromagnetic emissions. Attackers can use specialized equipment to capture and analyze these emissions, potentially reconstructing processed data or keystrokes. Understanding harmonics is crucial for implementing effective countermeasures, such as shielding and filtering, to prevent side-channel attacks that exploit these unintended signals. Proper management of harmonics helps secure electronic devices and protect confidential data from electromagnetic eavesdropping.