Muay Thai or Thai Boxing is a form of hard martial art practiced in large parts of the world, including Thailand and other Southeast Asian countries. The art is similar to others in Southeast Asia such as: pradal serey in Cambodia, lethwei in Myanmar, tomoi in Malaysia, and Lao boxing in Laos. Muay Thai has a long history in Thailand and is the country's national sport. Traditional Muay Thai practiced today varies significantly from the ancient art muay boran and uses kicks and punches in a ring with gloves similar to those used in Western boxing.

Muay Thai is referred to as "The Art of the Eight Limbs", as the hands, shins, elbows, and knees are all used extensively in this art. A practitioner of Muay Thai ("nak muay") thus has the ability to execute strikes using eight "points of contact," as opposed to "two points" (fists) in Western boxing and "four points" (fists, feet) used in the primarily sport-oriented forms of martial arts.

Technique
In its original form, Muay Thai consisted of an arsenal of nine weapons - the head, fists, elbows, knees and feet - known collectively as na-wa arwud. However in modern Muay Thai, both amateur and professional, headbutting an opponent is no longer allowed.

To strike and bind the opponent for both offensive and defensive purposes, small amounts of stand-up grappling are used: the clinch. Formal Muay Thai techniques are divided into two groups: Mae Mai or major techniques and Luk Mai or minor techniques. Muay Thai is often a fighting art of attrition, where opponents exchange blows with one another. This is certainly the case with traditional stylists in Thailand, but is a less popular form of fighting in the contemporary world fighting circuit. With the success of Muay Thai in mixed martial arts fighting, it has become the de facto martial art of choice for competitive stand-up fighters. As a result, it has evolved and incorporated much more powerful hand striking techniques used in western style boxing and the Thai style of exchanging blow for blow is no longer favorable. Note: when Muay Thai fighters compete against fighters of other styles (and if the rules permit it), they almost invariably emphasize elbow (sok) and knee (kao) techniques to gain a distinct advantage in fighting. Almost all techniques in Muay Thai use the entire body movement, rotating the hip with each kick, punch, and block. The rotation of the hips in Muay Thai techniques, and intensive focus on "core muscles" (such as abdominal muscles and surrounding muscles) is very distinctive and is what sets Muay Thai apart from other styles of martial arts.

Wai kru, ram muay and round definition
Prior to the start of the first round, both fighters shall perform the Wai Kru (paying respect to the teacher and Ram Muay (boxing dance), accompanied by the appropriate Thai traditional music, incorporating the Ching (cymbal), Klong khaek (tom-tom) and pi Java (Thai reed pipe). A Muay Thai match shall consist of five rounds, 3 minutes per round with a 1 or 2 minutes break between each round Any stoppage during the match for any reason, will not be counted as part of the 3 minutes round time.

Scoring
The standard scoring practice is as follows :

A: A strike either by a punch, kick, knee or elbow.

1. Scoring from a strike:
1.1. Points will be awarded for a correct Thai Boxing style, combined with hard and accurate strikes.
1.2. Points will be awarded for aggressive and dominating Muay Thai skill.
1.3. Points will be awarded for a fighter actively dominating his opponent.
1.4. Points will be awarded for the use of a traditional Thai style of defense and counter-attack.
1.5. Points will be deducted from a boxer who fouls or breaks the rules.

Mixed martial arts
Starting in the 1990s, Muay Thai has enjoyed a boost in popularity worldwide as it has been very effective in mixed martial arts training and competition. MMA artists such as Mauricio "Shogun" Rua, Wanderlei "The Axe Murderer" Silva, and Anderson "The Spider" Silva have combined many striking elements of Muay Thai with grappling, wrestling and Brazilian Jiu-Jitsu into a hybrid synthesis that has been highly effective in their fights. Other fighters that have used Muay Thai as their primary style in mixed martial arts include Duane Ludwig, Gina Carano, Thiago Alves, Cheick Kongo and more...

Source: wikipedia