When you die, the property you leave behind--called your "estate"--gets distributed according to the terms of your will. If you die without a will, your estate passes into the jurisdiction of your state's laws of intestate succession. To die "intestate" means to die without an effective will. While many things in the law vary from state to state, every state has laws pertaining to intestate succession.
Dying intestate doesn't necessarily mean that you never created a will. It can mean that your will wasn't executed and witnessed in accordance with state law. It can also come about because you or whoever drafted the will for you let beneficiaries be witnesses, or because your beneficiaries or someone you left out of the will successfully contested it. In these situations, you actually made a will, but the court could hold it invalid after your death. Because of these possibilities, it is extremely important to have a will done correctly, in accordance with all laws of the state where you live. Mistakes sufficient to invalidate your will probably won't be discovered until they can't be fixed anymore.
Preference for Surviving Spouse
The Uniform Probate Code, a version of which has been enacted in 18 states, expresses a preference for your surviving spouse if you die without a will. Under the code, your spouse receives all of your estate if you die with no descendants or parents, or if your descendants are also those of your spouse. The share of your spouse is smaller if you leave parents but no descendants, or if you have descendants that you didn't get through your surviving spouse. While the Uniform Probate Code hasn't been enacted in every state, a surviving spouse is an important figure in intestate succession everywhere.
If No Relatives Survive
If you leave no surviving spouse, your nearest relatives will inherit in order of their proximity to you in your bloodline. Your parents will come first, followed by your aunts and uncles and their children. If you leave no relatives behind, or the ones you leave aren't covered by your state's laws of intestate succession, your property will "escheat," which means to pass to the state. Because of this, it is important to make a will leaving your property to the friends or charities of your choice if you have no family.
Who Administers Your Estate If You Die Without A Will
Under a will, you appoint an executor, a person who handles the administration of your estate. If you die without a will, there is no executor. The court will have to appoint someone as administrator, who will carry out the duties normally seen to by an executor. The administrator will settle claims against the estate and figure out how to distribute everything that is left over among those people entitled to share under your state's intestate succession laws. As multiple relatives may be eligible to qualify as your administrator, the battle over your estate may begin even before the court appoints an administrator. Making a will can prevent your family from fighting over who gets to administer your estate, or prevent having that function be assigned by the court to a disinterested third party.