- Ninjas have proved to be an incredibly elusive subject. Historians suspect, however, that ninja tactics were first inspired by The Art of War, the Chinese military classic written by Sun Tzu in the 6th century BC. These skills - a mix of espionage and martial arts - were exported from China to Japan sometime during Japan's feudal era, although ninjutsu wouldn't emerge as a distinct form until at least the 14th century. Ninjas may have developed in response to the ruling samurai elite, and to their rigid honor code in particular: dueling clans could enlist a ninja to surreptitiously engage in dishonorable tactics, such as assassination or sabotage.
- Ninjas are thought to have exhibited a number of unorthodox tactics. They sometimes used gunpowder and smoke bombs to provide distraction, or even shells filled with sand and metal used to blind their enemies. Their tabi - boots with an opposable toe - served to silence their footsteps. Meanwhile, a small ring called a "shobo" could be used to directly target pressure points, and the "shuriken" included any number of sharp metal projectiles at their disposal.
- Modern-day images of ninjas typically take the form of a warrior dressed in all-black outfits. However, this dress code most likely stems from Japanese kabuki theater, not history. During kabuki performances, stagehands would dress in all black as they manipulated props throughout the show; the audience pretended that they were "invisible." Ninja characters would dress identically, thereby remaining "invisible" until they attacked. Working ninjas typically wore lightweight jackets and short trousers (called "kobakama"), although they did often wear a black cowl. They may also wear the same armored sleeves and shinguards - known as "kote" and "suneate" - worn by samurai.
- In the American martial arts community, the 1980s witnessed an impressive "ninja boom," during which time the number of schools claiming to teach "ninjutsu" increased dramatically. But as an institution, ninjas thrived on underground dealings and secret tactics: consequentially, the claims of many modern-day institutions to teach authentic "ninjutsu" martial arts - often referred to as "neo-ninja" schools - can hardly be conclusively proven. Japan, however, is indeed home to two schools which once provided elite ninjutsu training - the Iga School in Iga City, and the Koga School in Koka City.
- Ninjas have been resurrected - in the same vein as pirates, or zombies - as pop cultural icons. Their mysterious history provides a compelling tabula rasa for writers and historians, and their extreme skills leave them open for parody and emulation. The myth of the ninja maintains a strong cache in Japan; just outside of Osaka, the Japanese city of Iga Ueno is home to a popular ninja museum. Particularly in the western world, ninja imagery has been used more as a source of entertainment, such as in the web serial, "Ask a Ninja."
