The curveball, is a type of pitch in baseball thrown with a characteristic grip and hand movement that imparts forward spin to the ball. It is therefore considered a type of breaking ball (referring to the sense of the word break as in to to quickly or suddenly move).
As opposed to a fastball which has only backspin, the curveball instead has topspin that causes it to drop more as it is in flight. Additionally, because of mechanics of the throw, the pitch is usually significantly slower than the fastball.
The unique trajectory and speed of the curveball is used to disrupt the batter’s timing and/or aim. Curveballs may further trick the opponent by first appearing to be a ball while then curving into the strike zone. Likewise, a curveball may appear to be headed for the strike zone and end up curving outside.
The curveball is a popular and effective pitch in professional baseball. It does, however, require mastery and the ability to pinpoint the thrown ball’s location. There is generally greater chance of throwing a wild pitch when throwing the curveball. Additionally, an attempted curveball which fails to break as much as intended (referred to as a hung curveball, as in the ball is hanging tantalizingly for the batter) can be much easier to hit for batters. But once mastered, the curveball (aside from the changeup) is one of the most effective off-speed pitches in baseball.
The specific trajectory and speed of a curveball vary among throwers. As with fastballs, a specific pitcher’s curveball may have additional motions vertically or laterally. With some pitchers, the separation between curveball and other pitches such as slider and slurve, may be difficult to detect or even describe. However, the curveball generally is thrown in a similar fashion.
When throwing a curve, the pitcher creates downspin by rolling his palm and fingers over the top of the ball while releasing it. The direction of the break depends on the axis of spin on the ball. There are many variations of the curveball, but most are described in terms of their movement when superimposed on a clock. A “12–6” or “overhand” has a more or less straight downward action as it approaches the plate (imagine the face of a clock), while more sweeping curveballs might be described as “1–7” or “slurves”.
There is no specific amount that the ball breaks, but the deviation from a fastball trajectory becomes progressively greater as the ball approaches the plate. The amount of breaking is normally determined by the amount at which the pitcher snaps his wrist. A quick hard snap will cause more of a break than a looser snap. Some use a more looping slow curve and some use a harder, faster slurve.Physics of a Curveball
Generally the Magnus effect describes the laws of physics that make a curveball curve. A fastball travels through the air with backspin, which creates a high-pressure zone in the air ahead of and under the baseball. The baseball’s raised seams augment the ball’s ability to churn the air and create high pressure zones. The effect of gravity is partially counteracted as the ball rides on and into energized air. Thus the fastball falls less than a ball thrown without spin (neglecting knuckleball effects) during the 60 feet 6 inches it travels to home plate.
On the other hand, a curveball, thrown with topspin, creates a high-pressure zone on top of the ball, which deflects the ball downward in flight. Instead of counteracting gravity, the curveball adds additional downward force, thereby gives the ball an exaggerated drop in flight.
At the professional level, a curveball is usually about 20 miles per hour slower than a fastball.Real or Illusion?
There has been debate on whether a curve ball actually curves or is an optical illusion. In 1949, Ralph B. Lightfoot, an aeronautical engineer at Sikorsky Aircraft, used wind tunnel tests to prove that a curve ball does in fact actually curve. However, optical illusion caused by the ball’s spinning may play an important part in what makes curve balls difficult to hit. The curveball’s trajectory is smooth, however the batter perceives a sudden, dramatic change in the ball’s direction. When an object that is spinning and moving through space is viewed directly, the overall motion is interpreted correctly by the brain. However, as it enters the peripheral vision, the internal spinning motion distorts how the overall motion is perceived. A curveball’s trajectory begins in the center of the batter’s vision, but overlaps with peripheral vision as it approaches the plate, which may explain the suddenness of the break perceived by the batter. On whether a curve ball is caused by an illusion, Baseball Hall of Fame pitcher Dizzy Dean has been quoted in a number of variations on this basic premise: “Stand behind a tree 60 feet away, and I’ll whomp you with an optical illusion!”Technique
To throw a curveball correctly, proper spin must be given to the ball as it is released. Pitchers usually position their index finger aside one of the ball’s raised seams on the horseshoe part of the laces for more leverage in spinning the baseball. They bring their arm through the air in a “karate chop” motion. At the release point they then roll their hand over the top of the ball turning the back of their hand to the plate in order to throw it forward with downspin. If this movement is poorly executed the ball will have lazy spin, not break in flight, and be much easier to hit (the “hanging curve”).
When thrown correctly, it could have a huge break from seven to as much as 20 inches in comparison to the same pitcher’s fastball. .Nicknames
As with most facets of the sport of baseball, a colorful variety of nicknames is used to describe the curveball pitch. Popular nicknames include “the bender” and “the hook” (both describing the trajectory of the pitch), “‘Uncle Charlie,” “the hammer,” “yakker,” and “Public Enemy No. 1.” 
It is also referred to commonly as “the deuce” or “number two” because catchers have traditionally signaled their pitcher to throw the curveball by showing two fingers.Safety
A curveball, because of the risk of injury to the pitcher’s elbow and shoulder, is usually considered a more advanced pitch, geared towards pitchers with more developed and mature arms. It is suggested that the pitcher be near 16 to 18 years old before attempting a curve ball. This restriction is not due to the ability to learn how to throw a curveball; rather, the restriction is advised to allow for proper maturity of the pitcher’s arm. Generally, in most children, the cartilage and tendons in a pitchers arm have not yet been developed and could receive micro-tears that can permanently damage a pitcher’s arm.
The parts of the arm that are most commonly injured by the curveball are the ligaments in the elbow, the biceps and the forearm muscles.
The technique can also influence the likelihood of injury, such as whether the pitcher snaps their wrist, or twists their arm.History
Baseball lore has it that the curveball was invented in the early 1870s by Fred Goldsmith or Candy Cummings (it is debatable). An early demonstration of the “skewball” or curveball occurred at the Capitoline Grounds in Brooklyn in August, 1870 by Fred Goldsmith. In 1869, a reporter for the New York Clipper described Phonney Martin as an “extremely hard pitcher to hit for the ball never comes in a straight line‚ but in a tantalizing curve.” If the observation is true, this would pre-date Cummings and Goldsmith. In 1884, St. Nicholas, a children’s magazine, featured a story entitled, “How Science Won the Game”. It told of how a boy pitcher mastered the curve ball to defeat the opposing batters. In the early years of the sport, use of the curveball was thought to be dishonest and was outlawed, but officials could not do much to stop pitchers from using it. In the past, major league pitchers Bob Feller, Virgil Trucks, Herb Score, Camilo Pascual and Sandy Koufax were regarded as having outstanding curveballs. Steve Carlton is said to have had the best curveball in the recent modern era.Other notable pitchers who throw or threw great curveballs since 1900 are/were Barry Zito, Adam Wainwright, Tim Lincecum, A.J. Burnett, Sal Maglie, Dwight Gooden, Nolan Ryan, David Wells, Darryl Kile, Matt Morris, Orel Hershiser,Tom Gordon, Aaron Sele, Tommy Bridges, Bert Blyleven, Stephen Strasburg, and Mordecai “Three Finger” Brown.
And that’s the history of the curveball.
LOL AT THE GIF.
THAT GIF RULEZ.