A punch is a striking blow with the closed fist. It is used in some martial arts and combat sports, most notably boxing where it is the only type of offensive technique allowed. In sports, hand wraps or other padding such as gloves may be used to protect athletes and practitioners from injuring themselves.
The use of punches varies between different martial arts and combat sports. Styles such as boxing or Russian fist fighting utilize punches alone, while others such as kickboxing or karate may use punches as secondary to kicks. Others such as wrestling and judo do not utilize punches at all. There are many different types of punches and as a result, different styles encompass varying types of punching techniques.
A backfist is performed by forming a fist and striking with the tops of the two largest knuckles. A spinning backfist is performed when the attacker swivels 360 degrees before landing the punch, adding extra momentum to the attack. The fighter will lunge and begin spinning toward the side of the opponent of which fist he or she will attack with. Simpler terms, go to the left, spin to the left and connect with the left fist and vice versa.
The jab is a straight blow delivered (generally from a distance) with the arm above the lead foot ... The punch is quick and explosive." It is generally used for distraction, keeping distance, setting up, and defense.
By tucking the fingertips against the bottom knuckle of each finger, a long fist is formed. They offer decreased strength but increased reach. The striking surface is also narrower, which allows the fist to dig between ribs and other soft target areas.
A punch in which the arm is whipped sideways from the shoulder joint with minimal elbow bend. The name is derived from the motion, which mimics the action of manually cutting hay by swinging a scythe. The haymaker is considered an imperfect/impure punch, as the angle of approach is unsupported by the remainder of the forearm. Since a haymaker's power is derived completely from weight transfer and momentum instead of muscle contraction, a long windup is required to generate sufficient force. Haymakers, in the form of shoulder punches, are frequently used from a mounted position in mixed martial arts as part of the "ground and pound" method, as the legs cannot be used to generate power. When thrown from standing, these punches leave the person vulnerable to a counter punch during the wind up, if blocked, or if the haymaker misses. 
A semi-circular and vertical punch thrown with the rear hand. It is usually when the opponent is bobbing or slipping. The strategic utility of the drop relying on body weight can deliver a great deal of power.
A close range punch that is halfway between a hook and an uppercut. Shovel hooks are most commonly used to strike the body at a 45 degree angle. For example, a liver shot can be done using a shovel hook.
The fist is raised vertically towards the target, usually the head or upper body. Since most guards are held with the arms in a vertical position, the uppercut can be used to avoid the opponent's attempts at blocking.
This is a punch used in Sambo and MMA that starts with a forward motion of the shoulders, which causes the bent arm to whip forward to the opponent. This punch can often cause the opponent to be put in a clinch if it misses at close range.
A superman punch or diving punch is a technique used in Muay Thai, full contact karate and mixed martial arts fighting. The striker will lunge toward the opponent pushing off with the back foot punching with the opposite arm of the leg used to push off with although there may be variations in the name and technique, depending on the fighting style. The pose should resemble that of Superman, hence the name.
A punch that takes your enemy by surprise, possibly knocking them out or otherwise incapacitating them. Could be an unexpected blow to the stomach or a strike from behind that the victim did not see coming.
In boxing, punches are classified according to the motion and direction of the strike; contact is always made with the knuckles. There are four primary punches in boxing: the jab, cross, hook, and uppercut.
A karateka performing a 'reverse punch' or gyaku zuki
Punching techniques in Karate are called tsuki or zuki. Contact is made with the first two knuckles (seiken). If any other part of the hand is used to strike with, such as the back of the fist (uraken) or the bottom of the fist (tetsui), then the blow is classified as a strike (uchi).
Karate punches include the thrust punch oi-zuki made using the lead-hand, straight punch choku-zuki, reverse punch gyaku-zuki, made from the opposite hand, and many other variations.