A will governs the administration and disposition of assets upon the death of a person. Because a will can be changed at any time and only operates upon death, a will is only a will once a person dies -- and after it has been accepted by the probate court. Wills must be in writing; and if typed, a will must be witnessed by at least two people who are not named in the will. Courts also will recognize a will done in handwriting.
Typically the will nominates a fiduciary to perform the estate administration, called an "executor." It is also common for the will to waive the requirement (and expense) of a bond.