text: what is offences system of basketball ?   first of all, it isn't offences, it's offense. now, i don't understand what you're asking, but here you go: . . . . although the rules do not specify any positions whatsoever, they have evolved as part of basketball. during the first five decades of basketball's evolution, two guards, two forwards, and one center were used. since the 1980s, more specific positions have evolved, namely point guard, shooting guard, small forward, power forward and center. on some occasions, teams will choose to use a three guard offense, replacing one of the forwards or the center with a third guard.  two main defense concepts are used: zone defense and man-to-man defense. zone defense involves players in defensive positions, guarding whichever opponent is in their zone. in man-to-man defense, each defensive player guards and follows a specific opponent and tries to prevent him from taking action. variations of these two main structures are used.  offensive plays are more varied, normally involving planned passes and movement by players without the ball. a quick movement by an offensive player without the ball to gain an advantageous position is a cut. a legal attempt by an offensive player to stop an opponent marking a teammate, by standing in the defender's way such that the teammate cuts next to him, is a screen or pick. the two plays are combined in the pick and roll, in which a player sets a pick and then "rolls" away from the pick towards the basket. screens and cuts are very important in offensive plays; these allow the quick passes and teamwork which can lead to a successful basket. teams almost always have several offensive plays planned to ensure their movement is not predictable. on court, the point guard is generally responsible for indicating which play will occur.  defensive and offensive structures, and positions, are more emphasised in higher levels in basketball; it is these that a coach normally requests a time-out to discuss.   shooting   player releases a short jump shot, while her defender is either knocked down, or trying to "take a charge."shooting is the act of attempting to score points by throwing the ball through the basket. while methods can vary with players and situations, the most common technique can be outlined here.  the player holds the ball to rest in the dominant hand's fingertips (the shooting arm) slightly above the head, with the other hand on the side of the ball. the ball is shot by extending the shooting arm to become straight; the ball rolls off the finger tips while the wrist completes a full downward flex motion. generally, the non-shooting arm is only used to guide the shot, not to power it.  players often try to put a steady backspin on the ball to deaden its impact with the rim. the ideal trajectory of the shot is somewhat arguable, but generally coaches will profess proper arch. most players shoot directly into the basket, but in certain situations the shooter may use the backboard to redirect the ball into the basket.  the two most common shots are the set shot and the jump shot. the set shot is taken from a standing position, with neither foot leaving the floor, typically used for free throws. the jump shot is taken while in mid-air, near the top of the jump. this provides much greater power and range, and it also allows the player to elevate over the defender.  the best shooters have good coordination, balance, courage and are well practiced. realizing a shooting opportunity and using it is as important as basic technique; top players at the professional level rarely miss when given an unguarded look at the basket.   passing   carlos arroyo shown here with the utah jazz, left, passes to a teammate.a pass is a method of moving the ball between players. most passes are accompanied by a step forward to increase power and are followed through with the hands to ensure accuracy.  one of the most basic passes is the chest 