Metamaterials is an academic field and concept focused on designing and engineering artificial composite materials with structures at scales smaller than the wavelength of interest, enabling properties and functionalities for wave manipulation (e.g., electromagnetic, acoustic) not observed in naturally occurring materials. This research investigates the interplay between designed structure and material response to achieve unconventional phenomena like negative refractive index, cloaking, or perfect absorption, with significant implications for optics, acoustics, and energy applications.