A katana is a Japanese sword characterized by a curved, single-edged blade with a circular or squared guard and long grip to accommodate two hands. Developed later than the tachi, it was used by samurai in feudal Japan and worn with the edge facing upward. Since the Muromachi period, many old tachi were cut from the root and shortened, and the blade at the root was crushed and converted into katana. The official term for katana in Japan is uchigatana and the term katana often refers to single-edged swords from around the world. The katana is generally defined as the standard sized, moderately curved (as opposed to the older tachi featuring more curvature) Japanese sword with a blade length greater than 60.6 cm (23.86 inches) (Japanese 2 Shaku). It is characterized by its distinctive appearance: a curved, slender, single-edged blade with a circular or squared guard (tsuba) and long grip to accommodate two hands. With a few exceptions, katana and tachi can be distinguished from each other, if signed, by the location of the signature (mei) on the tang (nakago). In general, the mei should be carved into the side of the nakago which would face outward when the sword was worn. Since a tachi was worn with the cutting edge down, and the katana was worn with the cutting edge up, the mei would be in opposite locations on the tang. Western historians have said that katana were among the finest cutting weapons in world military history.
