Final answer:
A person who acts on behalf of or for the benefit of another is called a fiduciary. Fiduciaries have a legal or ethical obligation to prioritize the well-being and interests of the beneficiary over their own.
Step-by-step explanation:
A person who undertakes to act on behalf of or for the benefit of another is called a fiduciary. Fiduciaries are individuals who have a legal or ethical obligation to act in the best interests of another party, known as the beneficiary. They hold a position of trust and must prioritize the well-being and interests of the beneficiary over their own. Examples of fiduciaries include trustees who manage a trust, attorneys acting on behalf of their clients, and financial advisors handling investments for their clients.