Close-packed is a term used to describe a type of arrangement in which particles are packed together as closely as possible. This arrangement is also known as DENSE packing, and it is often used to describe the arrangement of atoms in a crystal lattice. DENSE packing is a common arrangement in many materials, including metals, ceramics, and polymers. The close-packed arrangement of particles results in a higher density than other arrangements, making it an ideal choice for many applications.