A shuriken (Japanese 手裏剣; literally: "sword hidden in the hand") is a traditional Japanese concealed weapon that was generally used for throwing, and sometimes stabbing or slashing. They are sharpened hand-held blades made from a variety of everyday items, such as needles, nails, and knives, as well as coins, washers, and other flat plates of metal. Shuriken is the name given to any small-bladed object, while shaken is traditionally used to indicate the well-known "throwing star".
Shuriken are commonly known in the West as throwing stars or ninja stars though they took many different shapes and designs during the time they were used. The major varieties of shuriken are the bō shuriken (棒手裏剣, stick shuriken) and the hira shuriken (平手裏剣, flat shuriken) or shaken (車剣, also read as kurumaken, wheel shuriken).
Shuriken were mainly a supplemental weapon to the more-commonly-used sword or other various weapons in a samurai warrior's arsenal, though they often played a pivotal tactical role in battle. The art of wielding the shuriken is known as shurikenjutsu and was mainly taught as a minor part of the martial arts curriculum of many famous schools, such as Yagyū Shinkage-ryū, Tenshin Shōden Katori Shintō-ryū, Ittō-ryū, Kukishin-ryū, and Togakure-ryū.