Metamaterials are artificial materials engineered to have properties not found in naturally occurring substances. They are designed to manipulate electromagnetic waves, such as light and sound, in unique ways. This allows them to achieve effects like negative refraction, which can bend waves in the opposite direction compared to conventional materials. These materials are made up of small, structured components that interact with waves at a scale smaller than the wavelength of the waves themselves. Applications of metamaterials include invisibility cloaks, superlenses, and improved antennas, making them a promising area of research in optics and telecommunications.