Metamaterials are artificial substances engineered to exhibit electromagnetic or acoustic properties that are not found in naturally occurring materials. These properties arise not from the inherent chemical composition of the material itself, but from the structural arrangement and geometric periodicity of their constituent elements, which act as subwavelength resonators. By controlling the material's effective parameters, such as the permittivity and permeability of free space, metamaterials can interact with waves in unprecedented ways, including enabling negative refraction or directional cloaking. Research into these structures spans various fields, leading to potential applications ranging from advanced radar-absorbing panels and ultra-compact antennas to highly efficient acoustic dampeners and superlenses for imaging.