In the sport of cricket, a bouncer (or bumper) is a type of delivery, usually bowled by a fast bowler. It is pitched short so that it bounces on the pitch well short of the batsman and rears up to chest or head height (or even higher) as it reaches the batsman.
Bouncers are used tactically to drive the batsman back on to his back foot if he has been freely playing front foot scoring shots, such as drives. To this end, bouncers are usually directed more or less at the line of the batsman's body. Note that, in contrast to baseball, aiming at the batsman is not illegal, and is a tactically useful part of the game.
A batsman may play a bouncer in either a defensive or an attacking way. If the batsman plays it defensively he aims primarily to avoid getting out, and secondarily to avoid being hit by the ball. For a head-high bouncer, these goals are achieved most easily by ducking under the ball. If the ball is at chest height, the batsman's best defence is to move on to his back foot, raise his bat vertically to chest height, and attempt to block the ball and direct it downwards to the pitch so as to avoid presenting a catch to a fielder. Sometimes the batsman will need to jump into the air to gain the necessary height to defend with the bat. This is particularly true for shorter batsmen like Sachin Tendulkar. Given these approaches, the bowler can hope to both intimidate the batsman somewhat, and possibly have the ball deflect off the bat at an awkward angle and produce a catch for a nearby fielder.
Conversely, the bouncer can be a very productive ball for the batsman, if he plays it in an attacking manner. The shot that is used to attack the bouncer is the hook shot. To play the hook shot the batsman moves his back foot backwards and towards the off side as the ball is being delivered. As the ball approaches, the batsman swivels from facing the off side to facing the leg side, while holding the bat horizontally. The batsman's aim is to hit the ball at high speed towards, into or over the leg side boundary. However, despite their run-scoring potential, hook shots frequently lead to wickets falling, particularly through balls hitting the top edge of the bat and being caught by leg side fielders. However, if the bouncer is misdirected by the bowler, and reaches the batsman on the off side of his wicket, the cut, uppercut or late cut can be played, either with the intention of guiding the ball along the ground, through a gap in the field setting, or over the infield for four or six.
Because of the potential danger to batsmen of being hit and to stop bowlers bowling bouncers all the time, there are laws in the Laws of Cricket governing how frequently a bowler may bowl bouncers. These laws take into account the relative skill of the batsmen.
Fast leg theory, the deliberate and sustained bowling of bouncers aimed at the body, was a tactic used by England against Australia in 1932/33, dubbed the Bodyline series by the Australians. This controversial tactic caused the Laws of Cricket to be reformed to prevent any recurrence.