Throughout the history of gloved boxing styles, techniques and strategies have changed to varying degrees. Ring conditions, promoter demands, teaching techniques, and the influence of successful boxers are some of the reasons styles and strategies have fluctuated.

Boxing styles are primarily defined as a combination of a boxer's offensive strategy, guard or defensive system, stance and behavior in the ring. Some boxers will change their style depending on who their opponent is, while others will use the same style regardless of their opponent. For example, Floyd Mayweather Jr. is primarily known for his technical defense, orthodox stance, crab style, out-fighting. Yet at times he would switch his style, showboating in the ring, fighting southpaw stance, using a high guard, and fighting on the inside.

A boxer's style often aligns with their physical attributes. For example, a boxer with a long reach is more likely to be an out-fighter that uses a long guard style compared to a fighter with a short reach. A fighter that is naturally right handed is also more likely to fight from an orthodox stance compared to a left-handed boxer that is more likely to fight from a southpaw stance. Though, physical attributes alone cannot predict a fighter's style as other factors such as gym culture and their trainer's philosophy also play a role.

Every boxer uses one of the four offensive strategies or styles: Swarmer, Out-Boxer, Slugger and Boxer-Puncher. While there are many different sub-categories for these styles, all boxers can be classified by one of the four main styles.

The Swarmer (inside fighter, pressure fighter, crowder) fights very aggressively and in close-quarters. This style involves bombarding the opponent with heavy attacks to prevent effective counters and wearing down the opponent's defenses by attrition. Notably, a swarmer is identified by their forward movement, prioritizing their positioning to throw numerous punches while crowding their opponent. Boxers using this style consistently stay within or at the edge of the punching range of their opponent, forcing their opponent to engage 'on the back foot,' either retreating or attempting counter punches. This tends to require a large investment of energy (cardio) on the part of both fighters, meaning one goal of this style is to exhaust their opponent. Swarmers typically also fight in crouches to heavily target body and to be able duck head shots more effectively. In-fighters rely on large volumes of punches for offensive and defensive purposes against while in close range and in clinching by landing punches while offsetting some of the long range and counter shots from their opponents.

Swarmer prioritize initiating engagements, usually by entering their opponent's punching range using a combination of footwork, feints and straight punches or uppercuts. Once inside of their opponent's range, their objective is to score (land punches), then quickly exit the engagement - ideally at the very edge of their opponent's punching range. A boxer may also exert pressure by initiating a clinch instead of exiting the engagement after punching while fighting in very close quarters. Ideally, the swarmer will seek to leverage their weight over their opponent in the clinch, forcing their opponent to expend energy.

An effective swarmer normally possesses a good "chin", as this style involves entering the punching range of their opponent before they can maneuver inside where they are more effective (one exception could be Floyd Patterson who was knocked down 20 times in 64 fights). Swarmers are often shorter than other fighters with shorter reaches, as these fighters more frequently have to get inside of their opponent's punching range to land punches, though this is not always the rule.

Commonly known swarmers are: