Minecraft wiki entry for Hitboxes, associated text: Have you ever heard somebody telling you to "break line of sight"? They are referring to making it so the mob can no longer see the player. The player has their own line of sight (red rectangle). The "line of sight" between mobs exists when the red rectangle of the player is visible from the red rectangle of the mob, and they are in range. This range varies from 20 blocks for most hostile mobs to a hundred blocks for ghasts and blazes, and is affected by factors like Blindness effect and wearing skulls.