The cricket ball is a hard, solid ball with an interior of cork and a leather case with a slightly raised sewn seam. For men's cricket, the ball must weigh between 5.5 and 5.75 ounces (155.9 and 163.0 g) and measure between 8 13/16 and 9 in (224 and 229 mm) in circumference. Balls used in women's and youth matches are slightly smaller.

A new, highly polished ball is used at the start of each innings in a match. A cricket ball may not be replaced except under specific conditions described in the Laws of Cricket:

• If the ball becomes damaged or lost.
• If the condition of the ball is illegally modified by a player.
• If, after a specified number of overs (80 in Test cricket), the captain of the bowling side requests a new ball.

Note that, unlike in baseball, the ball is not replaced if it is hit into the crowd - the crowd must return it. If the ball is damaged, lost, or illegally modified, it will be replaced by a used ball in similar condition to the replaced ball. A new ball can only be used after the specified minimum number of overs have been bowled with the old one.

Because a single ball is used for an extended period of play, its surface wears down and becomes rough. The bowlers will polish it whenever they can - usually by rubbing it on their trousers, producing the characteristic red stain that can often be seen there. However, they will usually only polish one side of the ball, in order to provide extra spin as it travels through the air. They may apply natural substances (i.e. saliva or sweat) to the ball as they polish it, but any other material is illegal.

The seam of a cricket ball can also be used to produce different trajectories through the air, with the technique known as swing bowling, or to produce sideways movement as it bounces off the pitch, with the technique known as seam bowling.

Since the condition of the cricket ball is crucial to the amount of movement through the air a bowler can produce, the laws governing what players may and may not do to the ball are specific and rigorously enforced. The umpires will inspect the ball frequently during a match. It is illegal for a player to:

• rub any substance apart from saliva or sweat onto the ball
• rub the ball on the ground
• scuff the ball with any rough object, including the fingernails
• pick at or lift the seam of the ball.

Despite these rules, it can be tempting for players to gain an advantage by breaking them. There have been a handful of incidents of so-called ball tampering at the highest levels of cricket, involving players such as Pakistani fast bowler Waqar Younis and former England captain Mike Atherton.

A new cricket ball is harder than a worn one, and is preferred by fast bowlers because of the speed and bounce of the ball as it bounces off the pitch. Older balls tend to spin more as the roughness grips the pitch more when the ball bounces, so spin bowlers prefer to use a worn ball. A captain may delay the request for a new ball if he prefers to have his spin bowlers operating, but usually asks for the new ball soon after it becomes available.

Cricket balls are traditionally dyed red, and red balls are used in Test and First-class cricket. White balls were introduced when one-day matches began being played at night under floodlights, as they are more visible at night. Many one-day matches are now played with white balls. Other colours have occasionally been experimented with, such as yellow and orange for improved night visibility, but the colouring process has so far rendered such balls unsuitable for professional play because they wear differently to standard balls.

The cricket ball is notoriously hard, and potentially lethal. Frederick, Prince of Wales, died of complications after being hit by one, and Glamorgan player, Roger Davis, was almost killed by one. Hence today's batsmen and fielders often wear protective headgear.

Alternatives to cricket balls

Sometimes alternatives to a real cricket ball may be preferred for reasons of safety, practice, availability and cost. Examples include a tennis ball (most favoured) or a plastic version of the cricket ball.

Many casual players use a tennis ball wrapped in layers of some type of adhesive tape (often electrical insulating tape), which makes the relatively soft tennis ball harder and smoother. This is commonly referred to as a taped ball. A common variant is to tape only half the tennis ball, to provide two different sides and make it easy to bowl with prodigious amounts of swing.

External link

• Cricket law 5 - the ball