An anchor is a heavy object tied to a ship with a very strong rope or iron chain.
When the ship stops sailing, the anchor is dropped into the sea.
The anchor helps to keep the ship in one place, instead of allowing it to float freely around the ocean.
A long time ago, anchors used to be just heavy baskets of stones.
Very large ships can need more than 1 anchor.
Today, anchors are usually made of forged steel.
Some anchors also have hooks to help keep them lodged in the sand of the seabed.