The line is the description of the direction in which a delivery is bowled. Thus a 'leg stump line' would be a ball aimed at the leg stump. It is fair to say that most deliveries by fast or medium paced bowlers are likely to be aimed at, or fractionally outside, the off-stump - the so-called 'corridor of uncertainty' so beloved by certain commentators. The effectiveness or otherwise of bowling a particular line will be inextricably connected with the length at which the ball is bowled.