Bark systems are the narrative infrastructure that generates contextual NPC dialogue during gameplay, outside of formal conversation systems. Guards commenting on the weather, shopkeepers greeting you differently based on your reputation, soldiers calling out tactical information, civilians reacting to your appearance or actions -- these are all barks. A good bark system tracks dozens of variables (time of day, player faction, recent events, NPC mood, proximity to landmarks) to select appropriate lines from massive databases. The challenge is making barks feel natural and varied rather than repetitive and robotic. Cooldown timers, priority systems, and contextual filtering all work to prevent the dreaded 'arrow in the knee' effect where a single line becomes memed for its repetition.