A trust is legal method used to transfer property and/or financial assets from your estate.
A Living Trust, which can be revocable or irrevocable is set up while a person is still living. With a revocable trust a person is allowed to retain control over the assets of the trust, as well as revoke or change the terms of the trust. With an irrevocable trust the assets no longer belong to the person and the trust cannot be revoked or changed, without consent of the beneficiary.
A Testamentary Trust does no go into effect until the person who had the trust created dies. Such trusts are often created as part of a will, and can be key features of proper estate planning, especially when the beneficiary is a minor.