Think of a trust entity as a person. Mostly because it is a person. Legally, it is a non-natural person, though specific definitions vary. The trust document is a "birth certificate" that spells out the various roles and functions of different "organ systems" of the person. The grantor gives the person life. The trustee is charged with maintaining the person and the beneficiaries get the property of the person after certain defined events occur. One natural person can have one or more functions within the non-natural person.