Electromagnetic radiation is energy that travels as waves, including radio, microwave, infrared, visible light, and more. In practical terms, it is the physical “carrier” behind wireless communication and many forms of remote sensing. It can interact with matter by being absorbed, reflected, scattered, or converted into electrical signals.
In cyber security, this matters because systems leak and receive information through electromagnetic fields. Attackers may exploit unshielded devices through eavesdropping on radio emissions, electromagnetic side channels, or interference and jamming. Defenders use the same physics for secure design: shielding, filtering, careful grounding, and controlled radio environments reduce unintended emissions and improve resilience. Understanding electromagnetic radiation helps analysts separate normal wireless behavior from suspicious signals and physical-layer attacks.