Will or Trust
The centerpiece of an estate plan is a Will (often called a Last Will & Testament) or a Trust. Though there are different types of Trust, the most common type is the Revocable Living Trust (also called a Living Trust).
A Will is a document that states what you want to happen with your assets when you die. A Will should name an Executor (also called Personal Representative) to administer your estate; pay all valid debts of the estate and distribution the remaining assets to the beneficiaries. A Will must also be probated; acknowledged as valid by the court before it can go into effect, and a Will cannot go into effect until you die.
A Revocable Living Trust is a three-party agreement that has a trustor (you), transferring title and management of your assets to a trustee (usually you during your life), for the benefit of the beneficiaries of the Trust (also you during your life). The Trust goes into effect as soon as it is signed, and assets transferred to the Trust can be immediately distributed upon your death.