Hook

For other uses, see Hook (disambiguation).
Lifting hook on a crane truck with a standard round hook and a gated opening
A cabin hook used as a latch for a wooden gate
Fish hooks are pointed and often barbed to help catch and tether a fish's mouth
The main anchor of IJN battleship Hiei with the classic double-hook design
Clothes hangers with a top hook to hang onto a crossbar or a clothesline
A grappling hook with multiple hooks to increase the chances of catching and anchoring onto a surface or an object
A crochet hook with a deep hooking groove near the tip, used to pull yarns during embroidery
A hook-and-eye clasp is composed of two pieces that are sewn to clothing, one of which serves as a hook while the other as a staple

A hook is a tool consisting of a length of material, typically metal, that contains a portion that is curved/bent back or has a deeply grooved indentation, which serves to grab, latch or in any way attach itself onto another object. The hook's design allows traction forces to be relayed through the curved/indented portion to and from the proximal end of the hook, which is either a straight shaft (known as the hook's shank) or a ring (sometimes called the hook's "eye") for attachment to a thread, rope or chain, providing a reversible attachment between two objects.

In many cases, the distal end of the hook is sharply pointed to enable penetration into the target material, providing a firmer anchorage. Some hooks, particularly fish hooks, also have a barb, a backwards-pointed projection near the pointed end that functions as a secondary "mini-hook" to catch and trap surrounding material, ensuring that the hook point cannot be easily pulled back out once embedded in the target.