What are metamaterials? What are the types and applications of metamaterials?

"Metamaterials (Metamaterials)" are artificial materials with extraordinary physical properties not found in natural materials. Metamaterials interact with light or other forms of energy in ways that do not exist in nature through micron/nanometer-scale patterns or structures designed around them, typical metamaterials are left-handed materials, photonic crystals, super magnetic materials, metallic water, etc.