In one sentence, describe what the following article is about:

Formal requirements for executing a valid will vary from state to state.  Before you create a will, you will need to review the requirements for your particular state to ensure that your will is enforceable upon your death.  Generally, a will must be:  In writing (either handwritten or typed)  Made by a person who is at least 18 years of age and able to understand the full meaning of the document.  Signed by the testator (person making the will) and two witnesses. If you are married, it is important that you determine whether you live in a community property or common law state before you write your will.  This distinction is important to ensuring that the terms of your will are carried out as you intended upon your death.     Community property states include: Arizona, California, Idaho, Nevada, New Mexico, Texas, Washington, Wisconsin, and Alaska. All other states follow the common law. In community property states, all property acquired during a marriage (known as "marital property") is divided equally between the spouses.  Upon his death, each spouse can dispose of his one-half share of marital property however he wishes.  However, he may not give away his spouse's share of marital property.  This means that if a wife writes a will bequeathing her entire estate to her daughter, one half of her estate will automatically be given to her husband instead, regardless of the terms of her will.  The only way to avoid this outcome is by agreeing to a different arrangement with your spouse in a prenuptial agreement. In common law states, a surviving spouse is not entitled to a one-half interest in all property acquired during marriage.  However, common law states still protect a surviving spouse from complete disinheritance, usually by guaranteeing that he receive at least one third of the deceased spouse's property.  Just as in community property states, this outcome can be overcome by entering a prenuptial agreement that sets forth a different arrangement. If you wish to ensure that your spouse receives less than one-half or one-third of your estate (depending on the exact proportion mandated by the law in your state), you will need to enter a prenuptial contract in which you agree to a different arrangement.   Write a contract that specifies what each spouse is entitled to receive upon death. To be valid, both parties must voluntarily agree to the contract, fully disclose their situations at the time the contract is executed and sign the contract before a public notary.  In addition, the agreement must be fair to both parties.    Keep in mind that, even if you write a prenuptial agreement specifying the share of your estate that will pass to your spouse upon your death, you will still need to a will that outlines the remaining distribution of your estate. If you have made a trust designating a beneficiary to receive property upon your death, you will need to review this document before creating your will.  Unlike those assets specified in your will, any assets included in your trust will transfer to the named beneficiary upon your death without passing through probate.   Make sure that you are aware of what assets (if any) you have in a trust and do not include those assets for distribution in your will.

Summary:
Review your state's requirements for executing a valid will. Determine whether your state follows community property or common law. Enter a prenuptial agreement. Review which assets (if any) you have in a trust.