Know your weapon.

Katana is the word for "sword" in the Japanese language. It is also used specifically for a type of Japanese backsword or longsword (daitō) in use after the 1400s: a curved, single-edged sword traditionally used by the samurai. Pronounced [kah-tah-nah] in the kun'yomi (Japanese reading) of the kanji , the word has been adopted as a loan word by the English language; as Japanese does not have separate plural and singular forms, both "katanas" and "katana" are considered acceptable plural forms in English.

The katana was typically paired with the wakizashi or shōtō, a similarly made but shorter sword, both worn by the members of the warrior class. It could also be worn with the tantō, an even smaller similarly shaped blade. The two weapons together were called the daishō, and represented the social power and personal honor of the samurai. The long blade was used for open combat, while the shorter blade was considered a side arm, more suited for stabbing, close quarters combat, and seppuku, a form of ritual suicide.

The katana was primarily used for cutting, and intended for use with a two-handed grip. It is traditionally worn edge up. While the practical arts for using the sword for its original purpose are now obsolete, kenjutsu and iaijutsu have turned into modern martial arts. The art of drawing the katana and attacking one's enemies is iaidō.

Authentic Japanese swords are fairly uncommon today, although genuine antiques can be acquired at significant expense. Modern katana and wakizashi are only made by the few licenced practitioners that still practice making these crafted weapons today, and even the "type 98 katanas" of World War II are rare.