A will or testament is a legal document that expresses a person's (testator) wishes as to how their property (estate) is to be distributed after their death and as to which person (executor) is to manage the property until its final distribution. For the distribution (devolution) of property not determined by a will, see inheritance and intestacy. Though it has at times been thought that a "will" historically applied only to real property while "testament" applied only to personal property (thus giving rise to the popular title of the document as "last will and testament"), the historical records show that the terms have been used interchangeably. Thus, the word "will" validly applies to both personal and real property. A will may also create a testamentary trust that is effective only after the death of the testator.

A will may also be revoked by the execution of a new will. Most wills contain stock language that expressly revokes any wills that came before them, because otherwise a court will normally still attempt to read the wills together to the extent they are consistent. In some jurisdictions, the complete revocation of a will automatically revives the next-most recent will, while others hold that revocation leaves the testator with no will, so that their heirs will instead inherit by intestate succession. Many Americans assume that they’re “too young” to need a Will. Some people believe that they don’t own enough assets or have a big enough net worth to necessitate a Will. You might even think it’s too late to start your first Will. But Trust & Will’s mission is to explain that regardless of your age, net worth, or stage in life, having a Last Will and Testament should be a top priority. We’re here to help as many people as we can protect their families and prolong their legacies. And the best way you can do that is to create your Last Will and Testament.

A will may not include a requirement that an heir commit an illegal, immoral, or other act against public policy as a condition of receipt. In community property jurisdictions, a will cannot be used to disinherit a surviving spouse, who is entitled to at least a portion of the testator's estate. In the United States, children may be disinherited by a parent's will,except in Louisiana, where a minimum share is guaranteed to surviving children except in specifically enumerated circumstances. There is no legal requirement that a will be drawn up by a lawyer, and some people may resist hiring a lawyer to draft a will. People may draft a will with the assistance of a lawyer, use a software product or will form, or write their wishes entirely on their own.