Shuriken, like kunai, are one of the more basic weapons seen in Naruto series. 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 centre, used for grabbing with a finger, to avoid cutting oneself, or to put thread through. The circle is also beneficial to the weapons overall aerodynamics, ensuring more accurate trajectories.
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 shuriken with bent points.
In the anime it was mentioned that there were cat shuriken.
Toroi of Kumogakure employs the use of slightly angular, square-shaped shuriken of varying sizes, ranging from those similar to the typically observed variant to ones nearly as large as his own person.
One of the weapons created by Iō was a useless shuriken that had so many points that it was impossible to grab.
Shuriken Launching Weapons
An unnamed Konoha shinobi used an unusual semi-circular launcher against Pain's Deva Path, containing a considerable quantity of shuriken, which could be launched simultaneously. This was achieved by holding onto a handle located at the crescents centre, while pulling out an attached length of chain in a manner similar to a ripcord that caused the shuriken to rotate, before firing the entirety in a single direction.
Toroi used a simple length of cord to thread numerous shuriken together, in such a manner that the entirety could be released and thrown consecutively with just a single motion.