An anchor chain is an essential component of a ship's anchoring system, which is used to secure the vessel to the bottom of a body of water. The anchor chain is made up of a series of interconnected metal links, and it is typically made of a strong, durable material such as steel or stainless steel. It is attached to the anchor at one end and to the ship at the other end, and it is used to hold the ship in place when it is anchored.