Quarterstepping

From Guild Wars Wiki

Quarterstepping takes advantage of the fact that after each attack there is a short period during which a character has not started their next attack yet but can still move. Between each attack there is a short amount of time during which a player can move before attacking again without increasing the amount of time between attacks to gain a positional advantage. Quarterstepping can be used to body block after a knockdown to allow more hits before a target starts kiting or to position behind someone to increase the chance of critical hits when they start kiting. It can also be used just to improve positioning without reducing damage pressure.

Quarterstepping is most easily achieved by attacking a target and just before the hit lands, clicking to move in the direction of desired repositioning and hitting space at the correct moment to initiate the attack again, but keyboard commands can also be used to move a character between attacks with an increased risk of accidentally canceling an attack before it lands. It works in exactly the same manner with attack skills as autoattacks.

Quarterstepping can be practiced just as easily on stationary targets such as the training dummies on the Isle of the Nameless as moving targets, but is slightly more difficult on a moving target.