Orbwalking is a technique used in some online multiplayer games, particularly in MOBAs (Multiplayer Online Battle Arenas), such as League of Legends or Dota 2.
In simple terms, orbwalking is a kiting technique that involves cancelling the attack animation of a hero/champion after launching an attack, then immediately moving forward before the next attack animation is due to begin. This allows the hero/champion to move away from the target while still dealing damage, effectively "walking" in a circular motion around the target.