A will is a legal document where a person, the testator, details the distribution of one’s assets and property in addition to appointing a person, the executor, to manage the distribution of the estate. A will can also create a testamentary trust, which will become an irrevocable trust upon death. A testamentary trust can be helpful in many ways, including holding assets for minors in trust instead of having the court appoint a guardian. A will and a testamentary trust, however, must go through the probate process in court.