A side-channel attack is a method used by hackers to gain information from a computer system by analyzing the physical effects of its operations. Instead of directly breaking encryption or software, attackers might observe things like power consumption, electromagnetic leaks, or even sound to extract sensitive data, such as cryptographic keys. These attacks exploit the unintentional information that systems emit during their normal operation. For example, by measuring how much power a device uses while processing data, an attacker can infer what calculations are being performed, potentially revealing secrets without needing to breach the system's defenses directly.