A fiduciary is a professional held to a fiduciary duty, meaning the person must act in their client's best interest not their own. Fiduciary financial advisors make investment decisions with you in mind and disclose any personal conflicts of interest, while an advisor who isn't a fiduciary may recommend products based on an expected commission or fee. Not all advisors who are members of a professional financial organization, for instance, have a fiduciary duty to clients, but certified financial planners do. It is part of their certification.