Brazilian Jiu-Jitsu (BJJ) is a martial art and combat sport that focuses on grappling and especially ground fighting with the goal of gaining a dominant position and using joint-locks and chokeholds to force an opponent to submit or be knocked out depending on what submission method is used. The art was based on early 20th century Kodokan Judo, which was itself then a recently-developed system (founded in 1882), based on multiple schools (or Ryu) of Japanese Jujutsu.

It promotes the principle that a smaller, weaker person using leverage and proper technique can successfully defend against a bigger, stronger assailant. It primarily uses Judo takedowns to gain the dominant position. BJJ can be trained for self defense, sport grappling tournaments (gi and no-gi) and mixed martial arts (MMA) competition. Sparring (commonly referred to as 'rolling') and live drilling play a major role in training, and a premium is placed on performance, especially in competition.

Prominence
Brazilian Jiu-Jitsu came to international prominence in the martial arts community in the 1990s, when Brazilian Jiu-Jitsu expert Royce Gracie won the first, second and fourth Ultimate Fighting Championships, which at the time were single elimination martial arts tournaments. Royce fought against often much-larger opponents who were practicing other styles, including boxing, shoot-fighting, karate, judo, tae kwon do and wrestling. It has since become a staple art for many MMA fighters and is largely credited for bringing wide-spread attention to the importance of ground fighting. Sport BJJ tournaments continue to grow in popularity worldwide and have given rise to no-gi submission grappling tournaments, such as the ADCC Submission Wrestling World Championship.

Ground fighting
BJJ is strongly differentiated by its greater emphasis on groundwork. This is due to both its radically different point-scoring system, and the absence of most of the judo rules that cause the competitors to have to recommence in a standing position. This has led to greater time dedicated to training on the ground, resulting in enhancement of judo's groundwork techniques by BJJ practitioners.

However, there are also many techniques that are allegedly created by BJJ, though they already existed in Kodokan judo. This misconception is often the result of incorrect assumptions by BJJ practitioners who simply assume that the techniques they learned in BJJ classes originated in BJJ, and it is also due in some instances to BJJ practitioners genuinely rediscovering techniques that they did not know already existed in judo, such as the Gogoplata.

Style of fighting
BJJ permits a wide variety of techniques to take the fight to the ground after taking a grip. Once the opponent is on the ground, a number of maneuvers (and counter-maneuvers) are available to manipulate the opponent into a suitable position for the application of a submission technique. Achieving a dominant position on the ground is one of the hallmarks of the BJJ style, and includes effective use of the guard position to defend oneself from bottom, and passing the guard to dominate from top position with side control, mount, and back mount positions. 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 in the sport. However, it is possible for a combat situation to continue even after a proper submission is performed.

Types of submission
The majority of 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 the body position which will force the joint to move past its normal range of motion, generally referred to as hyperextension. Pressure is increased in a controlled manner and released if the opponent cannot escape the hold and signals defeat by submitting. Opponents can indicate submission verbally or they can tap out (i.e. tap the opponent, the mat, or even themselves, several times.) A choke hold, disrupting the blood supply to the brain, can cause unconsciousness if the opponent does not submit soon enough.

Grading
The standards for grading and belt promotions vary between schools, but the widely accepted measures of a person's skill and rank in Brazilian Jiu-Jitsu are:

1. The amount of technical knowledge they can demonstrate, and
2. Their performance in sparring and competition.

A blue belt will typically take 1-3 years to earn. Depending on the amount of time the student puts in, and how quickly they learn. A purple belt can take 3-6 years to earn. Again, this depends largely on the individual student, and the frequency of training. A purple belt is generally accepted as being able to open his or her own school. Brown belt is considered an elite rank. Typically a student who has earned a brown belt will one day receive his or her black belt. Earning a black belt is not guaranteed in BJJ.

Back mount or rear mount is a dominant ground grappling position where one combatant is behind the other in such a way that he or she is controlling the combatant in front. Typically, the combatant in the inferior position is lying face-down, while the other combatant is sitting or lying on top. This is a very dominant, if not the most dominant position, since the top combatant can attack with strikes without the bottom combatant being able to see or defend.

The mount is a dominant ground grappling position, where one combatant sits on the other combatant’s torso with the face pointing towards the opponent's head. This is very favorable for the top combatant in several ways. The top combatant advantages are various chokeholds and joint locks which can be applied from the top, while such holds are not feasible from the bottom. The top priority for the bottom combatant is to sweep the opponent or transition into a better position such as the guard.

Guard passing is a multi-stage process. If the opponent is using a closed guard (i.e. his ankles crossed behind the back) the combatant has to open his legs. Once his legs are open you have to establish some sort of control over his hips and legs, and then finally you have to pass over, under or around his legs. Typically, but not always, successful BJJ guard passes end up in side mount.

A sweep is a technique used to transition from a neutral or inferior position to a dominant position, such as moving from under guard to full mount, hence the alternative term 'reversal' as the dominance of positions have been reversed. Examples include the scissor a where one leaps in the air with one's body side ways to take down the opponent with one's legs in a Y position.

Knee-on-stomach is a dominant ground grappling position where the top combatant places a knee on the bottom combatant’s torso, and usually extends the other leg to the side for balance. This position is typically obtained from side control, simply by rising up slightly and putting a knee on the opponent's stomach or chest.

A takedown is a martial arts and combat sports term for a technique that involves off-balancing an opponent and bringing him or her to the ground, typically with the combatant performing the takedown landing on top. The process of quickly advancing on an opponent and attempting a takedown is known as shooting for a takedown, or simply shooting. Takedowns are usually distinguished from throws by the type of motion involved, but sometimes the terms are used interchangeably for certain techniques.

A throw is a martial arts term for a grappling technique that involves off-balancing or lifting an opponent, and tossing them to the ground. It usually involves a rotating motion as opposed to a takedown). Typically the combatant performing the throw disconnects with the opponent, and ends balanced and on the feet. Throws can however also be followed into a top position, in which case the person executing the throw does not disconnect with the opponent.