History
A Japanese jujitsu expert and judoka, prizefighter, and former member of the Kodokan named Mitsuyo Maeda, also known as Count Koma, immigrated to Brazil in the 1910s where an influential businessman named Gastão Gracie helped him get established. In return for his aid, Maeda taught the fighting art of Jujitsu to Gastão's son Carlos, who then taught the art to his brothers, including Hélio Gracie.

Hélio had the opportunity to teach a class one day while Carlos was absent. He soon realized that most of the techniques could be adapted in a way to increase leverage therefore minimizing the force needed to execute the moves. Through Hélio's experiments early on, and constant technical refinement in training and real fighting, Brazilian Jiu-Jitsu as we know it today was created.

Some argue that the differences are more in culture and moral goals than in the physical principles and techniques of BJJ, however the considerable differences between BJJ and the Japanese styles include the use of strikes on the ground, and holds and joint locks forbidden in the sport of Judo.

Another main difference is that Judo, especially in its Olympic sport form, emphasizes throws, while Jiu-Jitsu focuses on submitting the opponent using arm locks, foot locks or chokes. Judo has a much higher amount of referee intervention; in Judo matches, the competitors are often returned to the standing position, while in Jiu-Jitsu matches, the participants are generally allowed to remain on the ground throughhout the entire match.

Other contributing factors to the stylistic divergence of BJJ include the Gracie's desire to create a national martial art, the influence of Brazilian culture, the Gracies emphasis on full-contact fighting and self-defense, the post World War II closing of the Kodokan by the American Occupation Authority (which were only allowed to reopen on the condition that emphasis be shifted towards sport), as well as the Gracies' own additions to the body of technique and theories regarding self-defense, martial arts and training methods; and, more recently, the influence of mixed-martial-art competitions such as the Ultimate Fighting Championship and Pride Fighting Championship.

Brazilian Jiu-Jitsu first became internationally prominent in the martial arts community in the 1990s, when Brazilian Jiu-Jitsu expert Royce Gracie won several single elimination martial arts tournaments called the Ultimate Fighting Championships against sometimes much larger opponents who were practicing other styles, including boxing, shoot-fighting, karate, judo, tae kwon do and wrestling. The remarkable success of BJJ versus the other martial arts has been attributed primarily to the unique Gracie methods, and the critical importance of ground grappling techniques neglected by those arts.

Techniques
Brazilian Jiu-Jitsu emphasizes ground fighting techniques and submission holds involving joint-locks and chokeholds. The premise is that most of the advantage of a larger, stronger opponent comes from superior reach and more powerful strikes, both of which are largely negated if grappling on the ground. BJJ includes many techniques to throw or tackle opponents to the ground, which are difficult to resist, even for people who are trained in their countermeasures.

Once the opponent is on the ground, a number of maneuvers (and counter-maneuvers) are available to manipulate the opponent into suitable position for the application of a submission hold. This system of maneuvering and manipulation can be likened to a form of kinetic chess when utilized by two experienced practitioners. A submission hold is the equivalent of checkmate.

Submission holds can be grouped into two broad categories: joint locks and chokes. Joint locks typically involve isolating an opponent's limb and creating a lever with your own body position which will force the joint to move past its normal range of motion. Pressure should be increased in a controlled manner and released if the opponent cannot escape the hold and signals defeat by submitting.

The commonly accepted form of submission is to tap the opponent, gym mat, or even yourself, three times. Verbal submission is also acceptable but less common.

Alternatively, one could apply a choke hold, disrupting the blood supply to the brain, causing unconsciousness if the opponent refuses to tap out.

Most BJJ "chokes" involve constriction of the carotid artery (causing hypoxia). This differs from the more instinctive choking movements which generally involve constriction of the windpipe (causing asphyxia). Though this distinction may at first seem subtle it is in fact significant (commonly referred to as "blood" and "air" chokes respectively). Air chokes are highly inefficient and may result in damage to the opponent's trachea, sometimes even resulting in death. In contrast, blood chokes directly cut the flow of blood off to the opponent's brain causing a rapid loss of consciousness without damaging the internal structure.

Being "choked-out" in this way is actually relatively safe as long as the choke is released soon after unconsciousness, letting blood (and therefore oxygen) back into the brain before the damages of oxygen deprivation begin. However, it should not be practiced in an unsupervised atmosphere.

The prevalence of the dangerous "air" chokes has actually led to the banning of chokeholds from some United States police departments. Because of the negative legal connotations of the words choke and even strangulation one is advised to use the term "lateral vascular restraint" when describing a blood choke used in a self-defense situation.

Brazilian Jiu-Jitsu's limitation to submissions without the addition of strikes while training allows practitioners to practice at full speed and almost full power, resembling the effort used in a real fight.

While many joint locks are permitted, most competitions bar or restrict some or all joint locks involving the knees and spine. The reasoning behind this being that the angles of manipulation required to cause pain are nearly the same to cause serious injury. Joint locks that require a twisting motion of the knee (called twisting knee locks or twisting knee bars) are usually banned in competitions as successfully completing the move nearly always results in permanent damage that requires surgery.

Similarly, joint manipulations of the spine are typically barred due to the inherent danger of crushing or mis-aligning cervical vertebrae. In Brazil, certain locks involving the knees and ankles are only allowed in competition starting at the brown belt. Any competitor from white to purple belt who tries any of these locks may be disqualified.

However, most joint locks involving the wrist, elbow, shoulder or ankle are permitted as there is a great deal more flexibility in those joints and are safe to use under tournament conditions. Also, in lower levels of competition, some fighters practice moves whose sole purpose is to inflict pain upon their opponent, in the hopes that they will tap out.

This includes driving knuckles into pressure points, holding their opponent's head in order to tire out the neck (called the "can opener" or kubi-hishigi) and putting body weight on top of the sternum, floating ribs, or similarly sensitive bones. These moves are not true submission moves and are avoided or brutally countered in middle to upper levels of competition. Generally, they are used as distractions, although an inexperienced fighter may tap out, despite being in no real danger.

The main emphasis in Brazilian Jiu-Jitsu is to dominate the opponent through skillful application of technique and force them to quit (submit). By using the techniques of Brazilian Jiu-Jitsu, a smaller practitioner, male or female, can control much larger and stronger opponents and actually force the larger opponent to submit.