Which of these tools is used in crochet?

A crochet hook is a tool used to make loops in thread or yarn and to interlock them into crochet stitches. It is basically a round shaft pointed on one end, with a lateral groove behind it. The point eases the insertion of the hook through the material being crocheted and the groove makes it possible to pull a loop back through the material. The shaft is then divided into a working area that determines the hook's nominal diameter and ensures the uniform sizing of the loops formed on it, and a handle.

Source: Skill Share