The person creating a will is called the "testator" and creates the document for any of the following purposes:
Nominate guardians for dependent children
Nominate a personal representative(s)
(otherwise known as an executor)
List beneficiaries of the estate
Create a testamentary trust
If a person passes without a last will and testament, the person is said to pass "intestate". The state of Arizona has a will that it use to handle the transition and distribution of your estate.
A will is valid in Arizona if it is in writing, signed by the decedent (or in the decedent's name by another person in the decedent's presence and direction) and signed by two witnesses. Holographic wills are handwritten wills and can be valid in Arizona if the will is entirely written in the testator's handwriting. However, a court may find reasons to doubt the validity of the will during probate. There is an amount of risk with holographic wills.
Having a will does not avoid probate. Probate is not a tax, it is a court process to validate and read the last will and testament. Learn more about probate.
The will also nominates guardians for dependent children. A court will still be required to officially appoint guardians, but a will helps a court by stating your wishes who shall take custody of children.
A last will and testament alone cannot hold assets after the testator (the person creating the will) passes. A trust of some type is needed. A will can create a testamentary trust after the testator passes to hold assets for distribution or estate tax reasons. Testamentary trusts do not help assets avoid probate.
A living trust does not eliminate the need for a last will and testament. They are used together, though a will used with a living trust is called a pour over will. Any assets not in the trust before the testator's passing can be directed to the trust by listing the trust as the beneficiary of the estate. These assets transferred after the testator's passing may have to go through probate first before being distributed by the trust. That is why it is important to transfer assets to a living trust before the testator's passing if avoiding probate is a goal.