The ball is a hard leather-seamed spheroid, with a circumference of 22.9 centimetres (9.0 in). The ball has a "seam": six rows of stitches attaching the leather shell of the ball to the string and cork interior. The seam on a new ball is prominent and helps the bowler propel it in a less predictable manner. During matches, the quality of the ball deteriorates to a point where it is no longer usable; during the course of this deterioration, its behaviour in flight will change and can influence the outcome of the match. Players will, therefore, attempt to modify the ball's behaviour by modifying its physical properties. Polishing the ball and wetting it with sweat or saliva is legal, even when the polishing is deliberately done on one side only to increase the ball's swing through the air, but the acts of rubbing other substances into the ball, scratching the surface or picking at the seam are illegal ball tampering.
Additional runs can be gained by the batting team as extras (called "sundries" in Australia) due to errors made by the fielding side. This is achieved in four ways: no-ball, a penalty of one extra conceded by the bowler if he breaks the rules; wide, a penalty of one extra conceded by the bowler if he bowls so that the ball is out of the batsman's reach; bye, an extra awarded if the batsman misses the ball and it goes past the wicket-keeper and gives the batsmen time to run in the conventional way; leg bye, as for a bye except that the ball has hit the batsman's body, though not his bat. If the bowler has conceded a no-ball or a wide, his team incurs an additional penalty because that ball (i.e., delivery) has to be bowled again and hence the batting side has the opportunity to score more runs from this extra ball.
Eden Gardens in Kolkata has hosted the most Tests, and also has the second-largest seating capacity of any cricket stadium in the world, being capable of holding more than 66,000 spectators. Founded in 1864, it is one of the most historical stadiums in India, having hosted numerous historical and controversial matches. Other major stadiums in India include the Feroz Shah Kotla Ground, which was established in 1883 and hosted memorable matches including Anil Kumble's ten wickets in an innings haul against Pakistan. For the last two years, the ground has been undergoing renovation.