You are “intestate” if you die without a will or trust. If this occurs, then state laws determine who inherits what when you die.
A testator (male) or a testatrix (female) is the person who creates a will.
A trust is a legal agreement or contract. A revocable living trust is often used in estate planning. “Revocable” means that you can change or amend it at any time; “living” means that you create it and benefit from it while you’re alive; and “trust” is an agreement. Think of a trust as a set of instructions.
A beneficiary is a person who will benefit from your estate planning instructions, whether through a gift in a will or instructions in a trust.