A fiduciary is legally obligated to act in a client's best interest, disclose conflicts of interest, and put the client's interests ahead of their own. Registered investment advisers are held to a fiduciary standard. Not every financial professional is a fiduciary, and the distinction affects how advice is given.
The clearest practical questions to ask are how the professional is compensated, whether they receive commissions or referral payments from third parties, and whether they will confirm their fiduciary obligation in writing.
Compensation structure is the most reliable signal, because it determines where the incentives point when nobody is checking.
This definition is provided for educational purposes. It is general information, not investment, tax, or legal advice, and it does not account for any individual circumstances.