Tanto represents a weapon with single-edged blade and a curved shape. It was designed for soft targets and was considered a hidden weapon of the samurai. Tanto was extremely effective in close fighting.

The word "tan" in "tanto" means "short"; "to" means "katana" (the same kanji as in Nihonto, but "to" is an "onyomi" pronunciation).  Tanto is a type of edged weapon with a very short blade of usually less than one "shaku" (30.3cm) from machi to kissaki. A tanto may or may not have a tsuba.

Tanto appeared during the Heian Period (795-1192 A.D.) and evolved as a weapon during Kamakura Period (1192-1333 A.D.). It is the period when tanto is not just a weapon but also a work of art.

It is also considered that tantos of different type were used for suicide ritual (seppuku, also hara-kiri). Still, it was mainly used by women samurai whose suicidal ritual was to cut their own throat. The men samurai used a wakizashi sword for the suicidal ritual which was different from the women's one (disembowelment).