Full contact karate is any format of karate where competitors spar (also called Kumite) full-contact and allow a knockout as winning criterion.
History
Full contact karate competition comes in several different formats developed for the art of karate at different times in different places. Some developed independently, others developed out of other full contact rule systems or from light contact rule systems.
There are no major unifying organizations in any of the different formats, and the rule details may change drastically between the many rival sport/style organizations and different promoters. Some organizations stick rigidly to one set of rules. Other use several rule formats harmoniously side by side. Some even have tournaments that switch rule formats between rounds of the same bout. Sometimes the differences between the different rules are large, and sometimes the only significant differences between different sport rules are the organizational structures that use them.
Different formats
Knockdown
One major format of full-contact sport karate is known as knockdown karate or sometimes Japanese full contact karate. This style of sport fighting was developed and pioneered in the late 1960s by the Kyokushin karate organization in Japan, founded by Korean-Japanese . In fighting the competitors traditionally wear no gloves, padding or body protection other than groin guards (although local regulations sometimes enforce exceptions to this tradition), but it is bare knuckle fighting. Grabbing and holding the opponent, including clinching, is not allowed under the basic- knockdown karate rules as used in Kyokushin, but are occasionally allowed in some variations used in other styles.
Points are scored by knocking the opponent out, down to the floor, by sweep and controlled follow up for half a point, or by otherwise visibly incapacitating them. Unless there is a knockdown or sweep, the bout is continuous, with stoppages only to break up locked clinches or if the fighters leave the fight area. Unlike American full-contact karate, or point karate, clean hits are not counted in and by themselves, as the scoring depends entirely on the effect of the hits, not on the formal or stylistic appearance of the techniques. No matter the perfection in execution of a technique, it will not score unless it visibly affects the opponent. In the same manner, if a technique does show a visible effect, it does not matter if it is executed in a manner regarded as inferior.
Common, minor variations to the basic-knockdown rules include Ashihara Karate and Enshin Karate knockdown rules that allow one-handed grabbing in order to execute throws to score points. Many other variations exist, some so extensive that they can no longer be classified as knockdown rules, and several other branches of full-contact karate (typically included in the "gloved", "MMA inspired" and "others" groups) originate as such a variation of the Knockdown karate rules.
Although this sport format originated with the Kyokushin karate organization, it has spread until now and it's used by many karate styles and organizations. Karate styles embracing these rules are often called knockdown karate styles, and these include both organizations that originated from Kyokushin, such as Shidōkan Karate, Ashihara Karate, Enshin Karate, Shindenkai and Seidokaikan (the style that originated the K-1), as well as styles that originated independently from Kyokushin such as Ryukyukan from Okinawa and Muso-Kai karate. (Muso-Kai started with Shorin Ryu, Knockdown styles were a huge influence later)
Though severely divided by rivaling styles and organizations (several of which use their own minor variations of the basic rules), and lacking a unifying sport organization, the sport of knockdown karate today is common all over the world. Despite the lack of a unifying sport organization to hold unifying championships (and the friction between the different styles and organizations), there is a long tradition in most knockdown karate organizations to hold special open-tournament knockdown karate events, where fighters from any knockdown karate (or any other) style and organization are welcome to participate.
American
A second full contact karate competition format is American full contact karate which was developed in the US during early 70s by borrowing rules, settings and gloves from western boxing, and adapting it. It is continuous fighting, where the bout is not broken for scoring, but point scores are summed up at the end of the bout. Protective equipment used is boxing gloves and often foot-pads, shin pads, and amateur boxing helmets.