Bob and Weave: The process of bobbing involves moving the head literally and beneath an incoming punch. As the punch of the opponent arrives, the boxer bends, and legs quickly and simultaneously shifts the body either slightly right or left. Once the punch has been dodged, the boxer weaves back to a straight position, emerging on either inside or outside of the opponent's still extended arm. To move outside the opponents extended arm is known as "bobbing to the outside".
Slip and/or Turn: Slipping and turning refers to rotating the body slowly so as to safeguard from an incoming punch. Just as the punch of the opponent arrives, the boxer rotates sharply his shoulder and hips. This facilitates the sideway movement of the chin and also allows the punch to slip past.
Block/Parry: Blocking or parrying happens when the hands of boxers is used as a defensive tool to turn aside the incoming attacks. As soon as the punch from the opponent arrives, the boxer delivers a sharp, lateral and open handed blow to the wrist or forearm of the opponent, redirecting the punch.
Peek-a-boo - This defensive shot is sometimes known as "earmuffs". This is the most common defensive systems. The hands are actually put next to each other in front of the face (like mentioned before fighters tend to vary the exact positioning in which they use it) 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).
As a boxer starts his career he is always taught to defend himself under every possible circumstance. And they are free to change guard once they gain experience. Defence moves helps to cover up a fighter well, bit there are holes as well. Hooks do damage by going around the hand by hitting just at the back of elbows.
Cross-armed - Forearms are placed top of each other horizontally in front of face with the glove of one arm being on the top of the elbow of the other arm. This particular style is hugely diverse when the rear hand vertically rises. This particular style is effective for reducing head damage. And the only punch that a boxer is susceptible to is the jab at the top of his 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.
Cover-Up: The process of covering up is the last resort to avoid a blow coming towards an unprotected body. Speaking generally, the hands are held high to safeguard the chin and head and also the forearms are tucked against the body to obstruct body shot. While a boxer is protecting his body, he rotates the hips and lets the incoming punches "roll" off the guard. In order to protect the head from severe blows, the boxer presses both fists against the front of the face with forearms parallel and in an outward facing position.
Philly Shell or Crab - The leading arm, is actually placed across the body, mainly somewhere between the chest and belly button and the leading arm rests on the differing side of the fighter's torso. The rear hand is placed at the side of the face (right side for orthodox fighters and left side for southpaws). The lead shoulder is brought in tight against the side of the face (left side for orthodox fighters and right side for southpaws). This particular style is often used by fighters who are known for counterpunch. In order to execute this shot, a fighter must be experienced and athletic. For the purpose of counterpunching, this style is also very effective, as it allows fighters to slip punches by rotating and dipping their upper body and causing blows to glance off the fighter.
Clinch: Clinching happens to be a rough way of grappling, and occurs when the distance between both fighters has closed and straight punches cannot be used. In this situation the boxer attempts to tie up or hold the opponent hand so he is unable to throw uppercuts or hook. In order to perform a clinch, the boxer loops both hands, around the outside of the opponents shoulder, shovelling back under the forearms to grasp the opponent's arms tightly against his own.
There are 3 major defensive positions, styles or guards used in boxing. All boxers have their typical and unique boxing styles. Some fighters may have their guard higher for a more head protection while others have their guard lower to provide better protection against body punches. Many fighters don't strictly use a single position, but rather adapt to the situation when choosing a certain position to protect them.