Intestate Succession

What happens when an individual dies without a will? In such cases, the individual is said to have died "intestate" and the decedent's assets are distributed pursuant to the laws of intestate succession for the applicable state. The best source I have found summarizing the intestate succession laws for each state is CCH (just click on the state of interest from chart at bottom of the page).

Let's assume you check the intestate succession laws for your state of residence discovering the distribute rules to be as you wish. For example, you are a single individual in Missouri with no children. The intestate laws for Missouri distribute a decedent's assets in such cases equally between the parents and siblings. Further assume this distribution is how you would have stated it in a last will if you created one so why bother executing a will? Several reason. First, naming an executor in your will makes the process that much easier for this individual to get named as executor (or personal representative, as the case may be) by the court. Secondly, your will can waive the requirement of the executor posting bond and authorized informal administration in many states. This makes the probate process cheaper and faster. If you have children, your last will is the place where you designate a guardian for your children should both parents die while they are minors.

FWIW, here is a web page giving its taken on why you should have a will.