Lead

From wiki.soldat.nl

Leading is the act of shooting ahead of the direction the desired target is moving in order that the bullet's and the target's trajectory intersect.

[edit] Analysis

When a soldier fires a bullet, depending on the weapon, it travels at speed x. Naturally the enemy is going to continue to move, therefore, a player must lead, or shoot ahead of the target in order to hit it.

Another important reason to lead is when you are lagging on a server (200+ ping). In this scenario leading by a few soldat feet may look like you are missing but in reality you are hitting your enemy.

[edit] Difficulties

As distance from target, player velocity, target velocity, bullet velocity, and gravity all play a role in mutilation, leading is difficult to do. Which is why most players simply start spraying bullets, and move aim using the line of tracer bullets. The reason those players die is because their targets know about leading, and start shooting ahead of you, allowing you to politely fly into their bullets.