Every Japanese Sword Is a Katana

They all look the same to me...

Japanese swords have evolved throughout Japanese history. That fact is entirely lost in popular culture, however, in which Japanese swords, regardless of design, are referred to as "katanas," because Katanas Are Just Better. In reality, the katana is a fairly recent weapon, relatively speaking, and hadn't been introduced yet during the classical period portrayed in many Jidai Geki films. Confusingly, in Japan, "katana" is sometimes used as a generic term for "sword", regardless of type.

Types of Japanese swords include:

• Tsurugi: The oldest type of Japanese sword, this was essentially a copy of the Chinese jian. Straight-bladed and double-edged, it did not resemble a katana at all.
• Tachi: Large, curved sword similar to a katana, but longer and more deeply curved, and worn with the edge down. This was the katana-equivalent that was in use throughout most of the medieval period in Japan.
• Katana: Shorter and not as curved as the tachi, the katana was introduced in the Muromachi period (mostly analogous to the Sengoku-jidai) in response to weapons control regulations that restricted the length of swords that could be carried. Most tachi were shortened into katana in response to the new laws (rather unfortunately, since there were a lot of very famous tachi that got modified), and new swords produced during the period were made with less and different zori (curvature) to reflect their wearer's greater likelihood of drawing and using them on foot in a duel than from a horse on a battlefield. Worn with the edge up. The uchigatana is the most common type of katana.
• Wakizashi: An Muromachi-period short sword, worn thrust sideways through the belt. (The name literally means "thrust sideways.") Sometimes worn together with a katana (this combination is called daishou) - this pair became the samurai's standard set of weapons during the Edo period, and was something of a status symbol. Their usage as such is actually much older, but only in Edo period it was strictly codified and actually enforced. Most samurai homes had a sword-rack near the door, so that visitors could leave their katana there but still have the wakizashi in case anything happened inside.
• Chiisagatana: A sword of intermediate length halfway between a katana and a wakazashi.
• Tanto: Basically a large dagger - generally mostly straight, and often rather wide. Was commonly worn with tachi as a part of an earlier form of the daisho, but diminished in popularity with the adoption of katana. In later eras they got stuck with the unfortunate name of harakirigatana, i.e. "the blade you use to cut your stomach open when committing suicide".
• Oo-dachi and Nodachi: Big honking swords larger than the norm. Kikuchiyo carries one in The Seven Samurai. These swords were often so large that wielders had to wear them on their backs.
• Zanbato: A BFS; essentially a humongous oodachi, roughly the size of a claymore. Like some of the more insane Zweihander designs, may never have been used in actual combat and made as more of a demonstration of iron forging prowess. Probably derived from the Chinese zhanmadao (as they both use the exact same characters), a sword that reputedly could cut through rider and horse at the same time.
• Nagamaki: Sword with a particularly long handle, roughly halfway between a sword and a halberd. Got their name (literally, "long winding") after the fact that their handles were usually simply wound with the cloth band, instead of the more elaborate woven patterns common for other Japanese swords.
• Naginata: A Blade on a Stick; Japan's equivalent to the halberd or glaive. Extremely effective on the battlefield, and the reason why Japanese armor includes suneate for the lower legs. Also favoured by the sohei before they were crushed by Nobunaga in the 15th century. Common troops abandoned this weapon for the spear (yari) in the 16th century, after which the "obsolete" naginatas were given to women, and became the characteristic weapon for samurai women.
• Daito: A catchall word for the larger sword in a Daisho pair. The word refers to the length of the blade, which was usually 70–90 cm.
• Shouto or Kodachi: A catchall word for the shorter sword in a Daisho pair. ("Kodachi" can also be used to refer to a blade that was similar to a wakizashi, but designed to be used by itself rather than in combination with a katana.)
• Ninjato/Ninjaken/Shinobigatana: A fictional sword similar to the katana, depicted as being a ninja's version of the weapon. It is usually straight-bladed, has a square guard, and is shorter than katana. Often it can hold small weapons in the hilt. Sometimes it is explained that the blade is of lower quality than a samurai's swords and cheaper to make, so it was used by ninja. Again, it's fictional, and never actually existed.
• Bokken: A wooden sword used for training. It is typically modelled on the katana but can also be based on other swords, such as the wakizashi or the tanto. With the right training, it too was a deadly weapon, and popular for ninja - after all, it's much easier (and cheaper!) to sneak a piece of wood around than sharp metal. A bokken is often designed to match the length and balance of the real sword, but to be heavier.
  • Shinai: Not really a sword, but a flexible shaft of tightly tied bamboo splinters that represents one in kendo to avoid injury. Still can be extremely painful and can give a serious injury if used wrong.
• Dosu: A very short sword that looks more like a long knife. Easy to conceal, and traditionally carried by the Yakuza.
• Shin-gunto: Mass-produced officers' blades used from 1934 to the end of WWII. Previously the Japanese military utilized the kyuu-gunto, which resembled a Western cavalry saber. However, nationalists demanded that a more "native" sword be carried, so a design closely patterned on the katana was adopted. Needless to say, these were of much lower quality than most Japanese swords - while some Type 94 shin-gunto used traditionally made blades, the Type 95 and 98 versions all used a blade that was essentially a piece of machined steel with an edge ground onto it.

See the Useful Notes page on Swords for more about, well, swords.