Magnetic fields are fundamentally composed of energy and can be understood as photon fields, according to modern physics. They are essentially relativistic electric fields, and quantum electrodynamics allows for the quantization of the electromagnetic field as a photon field. While some interpretations suggest that magnetic fields consist of virtual photons, this can be misleading. A solid understanding of magnetic fields requires foundational knowledge in electromagnetism and relativity, making it essential to start with basic texts like Halliday & Resnick. A comprehensive grasp of the subject is not achievable through brief explanations alone.