A bout in which the predetermined number of rounds passes is decided by the judges, and is said to "go the distance". The fighter with the higher score at the end of the fight is ruled the winner. With three judges, unanimous and split decisions are possible, as are draws. A boxer may win the bout before a decision is reached through a knockout; such bouts are said to have ended "inside the distance". If a fighter is knocked down during the fight, determined by whether the boxer touches the canvas floor of the ring with any part of their body other than the feet as a result of the opponent's punch and not a slip, as determined by the referee, the referee begins counting until the fighter returns to his or her feet and can continue. Should the referee count to ten, then the knocked-down boxer is ruled "knocked out" (whether unconscious or not) and the other boxer is ruled the winner by knockout (KO). A "technical knockout" (TKO) is possible as well, and is ruled by the referee, fight doctor, or a fighter's corner if a fighter is unable to safely continue to fight, based upon injuries or being judged unable to effectively defend themselves. Many jurisdictions and sanctioning agencies also have a "three-knockdown rule", in which three knockdowns result in a TKO. A TKO is considered a knockout in a fighter's record. A "standing eight" count rule may also be in effect, in which the referee counts no higher than eight to a boxer who regains his or her footing after a knockdown, allowing the referee time to assess if the boxer is able to continue.

In general, boxers are prohibited from hitting below the belt, holding, tripping, pushing, biting, spitting or wrestling. The boxer's shorts are raised so the opponent is not allowed to hit to the groin area. They also are prohibited from kicking, head-butting, or hitting with any part of the arm other than the knuckles of a closed fist (including hitting with the elbow, shoulder or forearm, as well as with open gloves, the wrist, the inside, back or side of the hand). They are prohibited as well from hitting the back, back of the neck or head (called a "rabbit-punch") or the kidneys. They are prohibited from holding the ropes for support when punching, holding an opponent while punching, or ducking below the belt of their opponent (dropping below the waist of your opponent, no matter the distance between). If a "clinch" – a defensive move in which a boxer wraps his or her opponents arms and holds on to create a pause – is broken by the referee, each fighter must take a full step back before punching again (alternatively, the referee may direct the fighters to "punch out" of the clinch). When a boxer is knocked down, the other boxer must immediately cease fighting and move to the nearest neutral corner of the ring until the referee has either ruled a knockout or called for the fight to continue.

Violations of these rules may be ruled "fouls" by the referee, who may issue warnings, deduct points, or disqualify an offending boxer, causing an automatic loss, depending on the seriousness and intentionality of the foul. An intentional foul that causes injury that prevents a fight from continuing usually causes the boxer who committed it to be disqualified. A fighter who suffers an accidental low-blow may be given up to five minutes to recover, after which they may be ruled knocked out if they are unable to continue. Accidental fouls that cause injury ending a bout may lead to a "no decision" result, or else cause the fight to go to a decision if enough rounds (typically four or more, or at least three in a four-round fight) have passed.

Punches
There are four basic punches in boxing: the jab, straight right/left hand, hook and uppercut. If a boxer is right-handed (orthodox), his left hand is the lead hand and his right hand is the rear hand. For a left-handed boxer or southpaw, the hand positions are reversed. For clarity, the following discussion will assume a right-handed boxer.

Jab - A quick, straight punch thrown with the lead hand from the guard position. The jab is accompanied by a small, clockwise rotation of the torso and hips, while the fist rotates 90 degrees, becoming horizontal upon impact. As the punch reaches full extension, the lead shoulder can be brought up to guard the chin. The rear hand remains next to the face to guard the jaw. After making contact with the target, the lead hand is retracted quickly to resume a guard position in front of the face. The jab is recognised as the most important punch in a boxer's arsenal because it provides a fair amount of its own cover and it leaves the least amount of space for a counter punch from the opponent. It has the longest reach of any punch and does not require commitment or large weight transfers. Due to its relatively weak power, the jab is often used as a tool to gauge distances, probe an opponent's defenses, harass an opponent, and set up heavier, more powerful punches. A half-step may be added, moving the entire body into the punch, for additional power. Some notable boxers who have been able to develop relative power in their jabs and use it to punish or 'wear down' their opponents to some effect include Larry Holmes and Wladimir Klitschko.

Cross - A powerful, straight punch thrown with the rear hand. From the guard position, the rear hand is thrown from the chin, crossing the body and traveling towards the target in a straight line. The rear shoulder is thrust forward and finishes just touching the outside of the chin. At the same time, the lead hand is retracted and tucked against the face to protect the inside of the chin. For additional power, the torso and hips are rotated counter-clockwise as the cross is thrown. Weight is also transferred from the rear foot to the lead foot, resulting in the rear heel turning outwards as it acts as a fulcrum for the transfer of weight. Body rotation and the sudden weight transfer is what gives the cross its power. Like the jab, a half-step forward may be added. After the cross is thrown, the hand is retracted quickly and the guard position resumed. It can be used to counter punch a jab, aiming for the opponent's head (or a counter to a cross aimed at the body) or to set up a hook. The cross can also follow a jab, creating the classic "one-two" combination. The cross is also called a "straight" or "right", especially if it does not cross the opponent's outstretched jab.

Hook - A semi-circular punch thrown with the lead hand to the side of the opponent's head. From the guard position, the elbow is drawn back with a horizontal fist (knuckles pointing forward) and the elbow bent. The rear hand is tucked firmly against the jaw to protect the chin. The torso and hips are rotated clockwise, propelling the fist through a tight, clockwise arc across the front of the body and connecting with the target. At the same time, the lead foot pivots clockwise, turning the left heel outwards. Upon contact, the hook's circular path ends abruptly and the lead hand is pulled quickly back into the guard position. A hook may also target the lower body and this technique is sometimes called the "rip" to distinguish it from the conventional hook to the head. The hook may also be thrown with the rear hand.

Uppercut - A vertical, rising punch thrown with the rear hand. From the guard position, the torso shifts slightly to the right, the rear hand drops below the level of the opponent's chest and the knees are bent slightly. From this position, the rear hand is thrust upwards in a rising arc towards the opponent's chin or torso. At the same time, the knees push upwards quickly and the torso and hips rotate anti-clockwise and the rear heel turns outward, mimicking the body movement of the cross. The strategic utility of the uppercut depends on its ability to "lift" the opponent's body, setting it off-balance for successive attacks. The right uppercut followed by a left hook is a deadly combination employing the uppercut to lift the opponent's chin into a vulnerable position, then the hook to knock the opponent out.

These different punch types can be thrown in rapid succession to form combinations or "combos". The most common is the jab and cross combination, nicknamed the "one-two combo". This is usually an effective combination, because the jab blocks the opponent's view of the cross, making it easier to land cleanly and forcefully.

A large, swinging circular punch starting from a cocked-back position with the arm at a longer extension than the hook and all of the fighter's weight behind it is sometimes referred to as a "roundhouse", "haymaker", or sucker-punch. Relying on body weight and centripetal force within a wide arc, the roundhouse can be a powerful blow, but it is often a wild and uncontrolled punch that leaves the fighter delivering it off balance and with an open guard. Wide, looping punches have the further disadvantage of taking more time to deliver, giving the opponent ample warning to react and counter. For this reason, the haymaker or roundhouse is not a conventional punch, and is regarded by trainers as a mark of poor technique or desperation. Sometimes it has been used, because of its immense potential power, to finish off an already staggering opponent who seems unable or unlikely to take advantage of the poor position it leaves the puncher in.

Another unconventional punch is the rarely used "bolo punch", in which the opponent swings an arm out several times in a wide arc, usually as a distraction, before delivering with either that or the other arm.

Defense
There are several basic maneuvers a boxer can use in order to evade or block punches, depicted and discussed below.

Slip - Slipping rotates the body slightly so that an incoming punch passes harmlessly next to the head. As the opponent's punch arrives, the boxer sharply rotates the hips and shoulders. This turns the chin sideways and allows the punch to "slip" past. Muhammad Ali was famous for extremely fast and close slips, as was an early Mike Tyson.

Sway or Fade - To anticipate a punch and move the upper body or head back so that it misses or has its force appreciably lessened. Also called "rolling with the punch" or " Riding The Punch".

Duck or Break - To drop down with the back straight so that a punch aimed at the head glances or misses entirely.

Bob and Weave - Bobbing moves the head laterally and beneath an incoming punch. As the opponent's punch arrives, the boxer bends the legs quickly and simultaneously shifts the body either slightly right or left. Once the punch has been evaded, the boxer "weaves" back to an upright position, emerging on either the outside or inside of the opponent's still-extended arm. To move outside the opponent's extended arm is called "bobbing to the outside". To move inside the opponent's extended arm is called "bobbing to the inside". Joe Frazier, Jack Dempsey, Mike Tyson and Rocky Marciano were masters of bobbing and weaving.

Parry/Block - Parrying or blocking uses the boxer's shoulder, hands or arms as defensive tools to protect against incoming attacks. A block generally receives a punch while a parry tends to deflect it. A "palm" or "cuff" is a block which intentionally takes the incoming punch on that portion of the defender's glove.

The Cover-Up - Covering up is the last opportunity (other than rolling with a punch) to avoid an incoming strike to an unprotected face or body. Generally speaking, the hands are held high to protect the head and chin and the forearms are tucked against the torso to impede body shots. When protecting the body, the boxer rotates the hips and lets incoming punches "roll" off the guard. To protect the head, the boxer presses both fists against the front of the face with the forearms parallel and facing outwards. This type of guard is weak against attacks from below.

The Clinch - Clinching is a rough form of grappling and occurs when the distance between both fighters has closed and straight punches cannot be employed. In this situation, the boxer attempts to hold or "tie up" the opponent's hands so he is unable to throw hooks or uppercuts. To perform a clinch, the boxer loops both hands around the outside of the opponent's shoulders, scooping back under the forearms to grasp the opponent's arms tightly against his own body. In this position, the opponent's arms are pinned and cannot be used to attack. Clinching is a temporary match state and is quickly dissipated by the referee.

Guards
There are several defensive positions (guards or styles) used in boxing. Within each style, there is considerable variation among fighters, as some fighters may have their guard higher for more head protection while others have their guard lower to provide better protection against body punches. Many fighters vary their defensive style throughout a bout in order to adapt to the situation of the moment, choosing the position best suited to protect them.

Boxers who use an upright stance protect their chin with the rear hand in either the low or mixed guard styles depicted below. Crouch fighters tend to use the "peek-a-boo" style, discussed below.

Peek-a-boo - Sometimes known as the "earmuffs," the hands are placed next to each other in front of the face (fighters tend to vary the exact positioning) and elbows are brought in tight to the body(this position can be achieved by bringing the elbows as close together while not straining yourself to do so). This defensive style is what a boxer is taught to do when he begins to box, after he gains experience he can decide to change or vary the guard. This style is middle-of-the-road style in terms of counterpunching and damage reduction. A boxer can counter punch from this stance, but it is difficult. However, there have been boxers who can do this very well. This defense covers up a fighter well, but there are holes. Hooks do damage by going around the hands and by hitting just behind the elbows. Winky Wright uses this style very well from a damage reduction stand point. Another famous example is Mike Tyson, who in his early career used the Peek-a-Boo with great success.

Cross-armed - The forearms are placed on top of each other horizontally in front of the face with the glove of one arm being on the top of the elbow of the other arm. This style is greatly varied when the back hand rises vertically. This style is the most effective for reducing head damage. The only head punch that a fighter is susceptible to is a jab to the top of the head. The body is open, but most fighters who use this style bend and lean to protect the body, but while upright and unaltered the body is there to be hit. This position is very difficult to counterpunch from, but virtually eliminates all head damage.

Philly Shell or Crab - The lead arm is placed across the torso usually somewhere in between the belly button and chest and the lead hand rests on the opposite side of the fighter's torso. The back hand is placed on the side of the face. The lead shoulder is brought in tight against the side of the face. This style is used by fighters who like to counterpunch. To execute this guard a fighter must be very athletic and experienced. This style is so effective for counterpunching because it allows fighters to slip punches by rotating and dipping their upper body and causing blows to glance off the fighter. After the punch glances off, the fighter's back hand is in perfect position to hit his out-of-positioned opponent. The shoulder lean is used in this stance. To execute the shoulder lean a fighter rotates and ducks when his opponent's punch is coming towards him and then rotates back towards his opponent while his opponent is bringing his hand back. The fighter will throw a punch with his back hand as he is rotating towards his undefended opponent. The weakness to this style is that when a fighter is stationary and not rotating he is open to be hit, so a fighter must be athletic and well conditioned to effectively execute this style. To beat this style fighters like to jab their opponent's shoulder causing the shoulder and arm to be in pain and to demobilize that arm.