The Master Key can open many early locked doors in Dark Souls and can be selected as a starting gift. It does not open every lock, but it bypasses several restrictions and can let experienced players reach areas earlier than intended.
This flexibility makes the Master Key one of the most influential starting gifts. A player who chooses it may access routes, shortcuts, and regions without first obtaining the ordinary key associated with each door. That can shorten progression or create difficult encounters far earlier than a first-time player expects.
The Master Key is not the same as the Residence Key, which opens specific doors in the Undead Burg. It also cannot replace the Crest of Artorias, a distinct item used to open the sealed entrance to the Forest Hunter area.
Because the gift changes routing rather than directly increasing combat power, it is especially popular with experienced players, speedrunners, and challenge-run participants.