Hexagonal Close-Packed (HCP) is a type of crystal structure found in various metals and minerals. In this arrangement, atoms are closely packed together in a hexagonal shape, maximizing space efficiency. Each atom is surrounded by twelve others, creating a dense and stable configuration. This structure is commonly observed in materials like zinc, magnesium, and titanium. The HCP arrangement allows for high density and strength, making it important in materials science and engineering. Understanding HCP helps in predicting the properties of these materials and their behavior under different conditions.