A trustee is a type of fiduciary who is in charge of the management of the assets and property in a trust; they can be an individual, institution, or combination of both according to an article from The Balance, “Types of Trustees and What They Do”.
If a trustmaker establishes a revocable living trust, then they serve as trustee themselves. Written into this trust should be a successor trustee who will take over management in the event the trustmaker dies or becomes mentally incompetent. On the other side, if an irrevocable trust is established, the grantor cannot name themselves as trustee. Instead, they must name an individual or institution to take control of the trust. Whether a person is a trustee of an irrevocable trust or a successor trustee of a revocable trust, they have the same duties.