Ethics: What exactly are "fiduciary duties?"

Is it part of the Standards? Code?

Fiduciary duties is a term describing responsibility to a third party for its financial wellbeing. it is your fiduciary duty as a trustee, for example, to do your best to do what is right for the trust. A fiduciary, used as a noun, is one who is responsible for anothers’ assets Someone else may have a better explanation.

act in best interest of client - be prudent, reasonable and use sound judgment

on the spot rolo.