Player versus Player, or PvP, is a term used in multiplayer games to refer to the conflict between two or more live participants.
PvP in Black Desert Online begins after a character is level 50. Everyone can attack everyone outside of safe zones (usually cities), but anyone that desires so can turn off a PvP indicator to show others they do not intend to take part on it. This indicator blocks the ability to inflict damage to other players, but they can still hit and kill you, albeit doing so will lower their karma.
Work in progress.