A organization of performing musicians in the Dragaeran Empire.
The guild presumably protects minstrels from dishonest tavern onwers, as well as assisting guild members with collecting debts owed to them. This prevents guild members from having to hire their own advocates to pursue individual claims.
Vlad Taltos wears a ring that identifies him to members of the Minstrel's Guild so that he can use them as an information network during his run from the Jhereg.