A Japanese sword (Japanese: 日本刀, Hepburn: nihontō) is one of several types of traditionally made swords from Japan. Bronze swords were made as early as the Yayoi period (1,000 BC – 300 AD), though most people generally refer to the curved blades made from the Heian period (794–1185) to the present day when speaking of "Japanese swords". There are many types of Japanese swords that differ by size, shape, field of application, and method of manufacture. Some of the more commonly known types of Japanese swords are the katana, tachi, ōdachi, wakizashi, and tantō.

The word katana was used in ancient Japan and is still used today, whereas the old usage of the word nihontō is found in the poem the Song of Nihontō, by the Song dynasty poet Ouyang Xiu. The word nihontō became more common in Japan in the late Tokugawa shogunate. Due to importation of Western swords, the word nihontō was adopted to distinguish it from the Western sword (洋刀, yōtō).^{[citation needed]}

Meibutsu (noted swords) is a special designation given to sword masterpieces which are listed in a compilation from the 18th century called the "Kyoho Meibutsucho". The swords listed are Koto blades from several different provinces; 100 of the 166 swords listed are known to exist today, with Sōshū blades being very well represented. The "Kyoho Meibutsucho" also listed the nicknames, prices, history and length of the Meibutsu, with swords by Yoshimitsu, Masamune, Yoshihiro, and Sadamune being very highly priced.

Each blade has a unique profile, mostly dependent on the swordsmith and the construction method. The most prominent part is the middle ridge, or shinogi. In the earlier picture, the examples were flat to the shinogi, then tapering to the blade edge. However, swords could narrow down to the shinogi, then narrow further to the blade edge, or even expand outward towards the shinogi then shrink to the blade edge (producing a trapezoidal shape). A flat or narrowing shinogi is called shinogi-hikushi, whereas a flat blade is called a shinogi-takushi.

The shinogi can be placed near the back of the blade for a longer, sharper, more fragile tip or a more moderate shinogi near the center of the blade.

The sword also has an exact tip shape, which is considered an extremely important characteristic: the tip can be long (ōkissaki), medium (chūkissaki), short (kokissaki), or even hooked backwards (ikuri-ōkissaki). In addition, whether the front edge of the tip is more curved (fukura-tsuku) or (relatively) straight (fukura-kareru) is also important.

The kissaki (point) is not usually a "chisel-like" point, and the Western knife interpretation of a "tantō point" is rarely found on true Japanese swords; a straight, linearly sloped point has the advantage of being easy to grind, but less stabbing/piercing capabilities compared to traditional Japanese kissaki Fukura (curvature of the cutting edge of tip) types. Kissaki usually have a curved profile, and smooth three-dimensional curvature across their surface towards the edge—though they are bounded by a straight line called the yokote and have crisp definition at all their edges. While the straight tip on the "American tanto" is identical to traditional Japanese fukura, two characteristics set it apart from Japanese sword makes: The absolute lack of curve only possible with modern tools, and the use of the word "tanto" in the nomenclature of the western tribute is merely a nod to the Japanese word for knife or short sword, rather than a tip style.

Although it is not commonly known, the "chisel point" kissaki originated in Japan. Examples of such are shown in the book The Japanese Sword by Kanzan Sato. Because American bladesmiths use this design extensively it is a common misconception that the design originated in America.