As with any adventure your character's time among the living will eventually draw to a close and he will die or depart this world in some other manner. During your time on the Sword Coast it is likely you will meet Myrkul - the god of Death - more than once in the Fugue plane. You pay an experience cost of 100 per character-level to be resurrected to the land of the living.
This cost does not decrease your level even if it is greater than the amount of experience you've earned. It also does not remain as an experience debt.
If you've died:[]
If your character has died he cannot recall anything that happened in the fugue or his encounter with Myrkul, or any players there. Sending in character tells from the fugue plane is also frowned upon as meta-gaming. In the event that your character met his demise at the hands of another player in a PvP situation the no-memory rule extends further than the stay in the Fugue. It means that your character cannot recall or remember how he died and what immediate events led up to his death.
Permanent Death:[]
Baldur's Gate does not have forced permanent death for characters. Dungeon Masters will never pursue such a thing unless a player consents. In that case it may be possible for the Dungeon Masters to organize some events leading to the character's permanent demise / retirement. At this point you can then delete the retired character via the RCR NPC in the nexus.