A crochet hook is a type of needle with a hook at one end used to draw thread through knotted loops. Only one crochet hook is needed to make crochet stitches. The crochet hook's earliest use appears to have been in the late 1700s or early 1800s.
Typical materials for crochet hooks are wood, plastic, casein, or aluminum. Historical examples also include bone, steel, porcupine quill, celluloid, agate, ivory, and fossilized mammoth ivory. They can have decorative handles. The handle may be shaped to fit the hand for easier use. Some hooks are made with wooden or plastic handles with the hook made of metal and inserted into the handle.
An alternative form is the Tunisian crochet hook, which is much longer than a regular crochet hook, in order to accommodate the multiple loops used in Tunisian crochet. A type of crochet needle with a hook at each end, known as a cro-hook, is used to make double-sided crochet pieces.
Although it is indicated above that there is a hook at one end (Double end crochet hooks) have a hook at both ends and are use for a different type of crocheting.