Your assets will go to whomever the state of Maine (or whatever state you are a resident when you die) thinks they should. When you die without a will you die “intestate” and the laws of intestacy kick in. Sometimes this can lead to disastrous results.
Say, for example, you own a home but have lived there with a life partner for many years. If you die without a will your life partner is not a beneficiary under the laws of intestacy. If you have no children, that house could go to parents, siblings, or even distant cousins that you may have nothing to do with or who could have financial problems or be in a nursing home.
The simplest way to ensure that your assets go to the people you want is to execute a will. (Trusts can work and have certain advantages, too.)