Shuriken

A shuriken, like kunai, is one of the more basic weapons seen in Naruto. They are sharpened, four-pronged metal stars, useful for throwing. Although small, they can be used to distract,pin down enemy shinobi, or if accurate enough, can be deadly. They have an open circle in the center, used for grabbing with a finger, to avoid cutting oneself, or to put thread through. The circle is also a benefit in aerodynamics, as it ensures more accurate trajectories.

Types of Shuriken
In addition to the basic shuriken, larger, arm-length shuriken have been seen in the series. They are usually carried on the back or stored in scrolls. The Fūma Shuriken is of a similar size, but is more lethal and can be folded together for easier storage. The shuriken of the Land of Birds are a little bit different. It has three-pronged metal stars instead of four. There have also been seen shurikens with bent points. In the anime it was mentioned that there were cat shuriken.

Trivia

 * The Shuriken used in the series are of the Hira Shuriken variety; four-point star-shaped disks, rather than the Bo Shuriken variety; which are straight, iron or steel throwing-spikes.