Taken from Wikipedia:
Jujutsu (also known as Ju-Jitsu, Jiu-Jitsu, or Jiujitsu), is Japanese martial art and a method of close combat for defeating an armed and armored opponent in which one uses no weapon, or only a short weapon.
"Ju" can be translated to mean "gentle, supple, flexible, pliable, or yielding." "Jutsu" can be translated to mean "art" or "technique" and represents manipulating the opponent's force against himself rather than confronting it with one's own force. Jujutsu evolved among the samurai of feudal Japan as a method for defeating an armed and armored opponent in which one uses no weapon, or only a short weapon. Because striking against an armored opponent proved ineffective, practitioners learned that the most efficient methods for neutralizing an enemy took the form of pins, joint locks, and throws. These techniques were developed around the principle of using an attacker's energy against him, rather than directly opposing it.
There are many variations of the art, which leads to a diversity of approaches. Jujutsu schools or ryu may utilize all forms of grappling techniques to some degree (i.e. throwing, trapping, joint locks, holds, gouging, biting, disengagements, striking, and kicking). In addition to jujutsu, many schools teach the use of weapons.
Today, jujutsu is practiced in both traditional and modern forms. Derived sport forms include the and martial art of judo, which was developed by Kano Jigoro in the late 19th century from several traditional styles of jujutsu, and Brazilian Jiujitsu, which was in turn derived from earlier (pre-World War II) versions of Kodokan judo.
History and Origin of Jujutsu
Several theories explain the origins of jujutsu. One theory holds that in the 17th century, a Chinese man named Chen Yuan Ping introduced the techniques of jujutsu to three ronin - Fukuno Hichiroemon, Miura Yojiemon, and Isogai Jirozaemon. The other theory propounded by the Yoshin Ryu holds that a doctor named Akiyama Shirobei from Nagasaki devised jujutsu upon his return from China where he learned the art of hakuda.
The term jujutsu was not coined until the 17th century, after which time it became a blanket term for a wide variety of grappling-related disciplines. Prior to that time, these skills had names such as "short sword grappling" (kogusoku koshi no mawari), "grappling" ( or kumiuchi), "body art" (taijutsu), "softness" (or yawara), "art of harmony" ( wajutsu, yawarajutsu), "catching hand" ( torite), and even the "way of softness" (judo) (as early as 1724, almost two centuries before Kano Jigoro founded the modern art of Kodokan Judo).
Today, the systems of unarmed combat that were developed and practiced during the Muromachi period (1333–1573) are referred to collectively as Japanese old-style jujutsu ( Nihon koryu jujutsu). At this period in history, the systems practiced were not systems of unarmed combat, but rather means for an unarmed or lightly armed warrior to fight a heavily armed and armored enemy on the battlefield. In battle, it was often impossible for a samurai to use his long sword, and would therefore be forced to rely on his short sword, dagger, or bare hands. When fully armored, the effective use of such "minor" weapons necessitated the employment of grappling skills.
Methods of combat (as mentioned above) included striking (kicking and punching), throwing (body throws, joint-lock throws, unbalance throws), restraining (pinning, strangling, grappling, wrestling) and weaponry. Defensive tactics included blocking, evading, off-balancing, blending and escaping. Minor weapons such as the tanto (knife), Kusari Fundokabuto wari (helmet smasher), and kakushi buki (secret or disguised weapons) were almost always included in Sengoku jujutsu. (weighted chain),
Development
In later times, other koyru developed into systems more familiar to the practitioners of Nihon jujutsu commonly seen today. These are correctly classified as Edo jujutsu (founded during the edo period): they are generally designed to deal with opponents neither wearing armor nor in a battlefield environment. Most systems of Edo jujutsu include extensive use of atemi waza (vital-striking technique), which would be of little use against an armored opponent on a battlefield. They would, however, be quite valuable in confronting an enemy or opponent during peacetime dressed in normal street attire (referred to as "suhada bujutsu"). Occasionally, inconspicuous weapons such as tanto (daggers) or tessen (iron fans) were included in the curriculum of Edo jujutsu.
Another seldom-seen historical side is a series of techniques originally included in both Sengoku and Edo jujutsu systems. Referred to as hojo waza ( hojojutsu, torinawa jutsu, nawa jutsu, hayanawa and others), it involves the use of a hojo cord, (sometimes the sageo or tasuke) to restrain or strangle an attacker. These techniques have for the most part faded from use in modern times, but Tokyo police units still train in their use and continue to carry a hojo cord in addition to handcuffs. The very old Takenouchi Ryu is one of the better-recognized systems that continue extensive training in hojo waza. Since the establishment of the Meiji period with the abolishment of the Samurai and the wearing of swords, the ancient tradition of Yagyu Shingan Ryu (Sendai and Edo lines) has focused much towards the jujutsu (Yawara) contained in its syllabus.
Many other legitimate Nihon jujutsu ryu exist but are not considered koryu (ancient traditions) such as Hakko Ryu. These are called either Gendai Jujutsu or modern jujutsu. Modern jujutsu traditions were founded after or towards the end of the Tokugawa (1868), when more than 2000 schools (ryu) of jujutsu existed. Various traditional ryu and ryuha that are commonly thought of as koryu jujutsu are actually gendai jujutsu. Although modern in formation, very few gendai jujutsu systems have direct historical links to ancient traditions and are incorrectly referred to as traditional martial systems or ryu. Their curriculum reflects an obvious bias towards Edo jujutsu systems as opposed to the Sengoku jujutsu systems. The improbability of confronting an armor-clad attacker is the reason for this bias.
Over time, Gendai jujutsu has been embraced by law enforcement officials worldwide and continues to be the foundation for many specialized systems used by police. Perhaps the most famous of these specialized police systems is the Keisatsujutsu (police art) Taiho jutsu (arresting art) system formulated and employed by the Tokyo Police Department.
If a Japanese based martial system is formulated in modern times (after Tokugawa) but is only partially influenced by traditional Nihon jujutsu, it may be correctly referred to as goshin (self defense) jutsu. Goshinjutsu is usually formulated outside Japan and may include influences from other martial traditions. Brazilian Jiujitsu, which was developed from judo, but with greater emphasis on ground grappling, is an excellent example of Goshinjutsu.
Jujutsu techniques have been the basis for many military unarmed combat techniques (including British/US/Russian special forces and SO1 police units) for many years.
Philosophy of Jujutsu
All Japanese jujutsu schools have cultural indicators that help give a sense of the traditional character of the school.
Japanese culture and religion have become intertwined into the martial arts. Buddhism, Shinto, Taoism and Confusian philosophy co-exist in Japan, and people generally mix and match to suit. This reflects the variety of outlook one finds in the different schools.
Jujutsu expresses the philosophy of yielding to an opponent's force rather than trying to oppose force with force. Manipulating an opponent's attack using his force and direction allows jujutsuka to control the balance of their opponent and hence prevent the opponent from resisting the counter attack.
The Japanese have characterised states of mind that a warrior should be able to adopt in combat to facilitate victory. These include: an all-encompassing awareness, Zanshin (literally "remaining spirit"), mushin, (literally "no mind") which allows immediate action without conscious thought; and a state of equanimity or imperturbability known as fudoshin (literally "immovable mind"). , in which the practitioner is ready for anything, at any time.