Reverb simulates the reflections that occur when sound bounces off surfaces in a physical space. Pre-delay is the gap before the first reflections arrive, which affects the perceived size of the room. Decay time controls how long reflections persist before fading to silence — short decay suggests a small, absorptive room, while long decay evokes a cathedral or concert hall. The wet/dry mix determines how much processed signal blends with the original. Subtle settings add depth without drowning clarity; heavy settings create ambient washes and atmospheric textures.