Laws governing wills vary from state to state and are usually located in a state’s statutes—in its estates code, for example. Generally, a will is a legal declaration of a person's intention or wish regarding the disposition of his property, the guardianship of his children, and the administration of his estate upon his death. It is said to be a means of transferring title to property. Any writing or declaration by which a person intends to dispose of his property or estate upon his death is a will, and if done as required by law, is entitled to probate as a will. A will vests no present interest in the property it intends to distribute—it is only effective upon the death of the person making the will (the testator). And a will is ambulatory—meaning the testator can change or revoke it during his lifetime.

A will may (1) direct how the testator's property should be disposed of upon his death; (2) direct how not to dispose of the testator's property, such as by expressly disinheriting a child or other heir; (3) revoke a prior will; and (4) appoint an executor of the testator's estate, and a guardian for the testator's children.

Some common types of wills include:

Holographic wills—a holographic will is a will that is written entirely in the testator's handwriting. A will intended by the testator as holographic will be enforced even though it contains words not in the handwriting of the testator, if such other words are not necessary to complete the will and do not affect its meaning. For example, an acknowledgment of a notary public and the notary public's signature are surplusage not necessary to complete the will and do not affect its meaning. A holographic will is not required to be attested by subscribing (signing) witnesses.

Attested wills—an attested will is a will that is attested to (declaring or swearing to the truth of) by two or more credible witnesses who are at least 14 years of age, and who sign their names to the will in their own handwriting in the testator's presence. An attested will can be handwritten by the testator, but usually is not.

Codicils—a codicil is a supplement to a previous will that adds to, modifies, or revokes one or more provisions of the earlier will.

In Washington State, wills are governed by the Revised Code of Washington (RCW), particularly in Title 11 which pertains to probate and trust law. A will in Washington is a legal document that expresses a person's wishes regarding the distribution of their property and the care of any minor children upon their death. To be valid, a will must meet certain legal requirements. Washington recognizes both holographic (handwritten) and attested wills. Holographic wills must be entirely in the testator's handwriting and signed by the testator, but they do not require witnesses. Attested wills, on the other hand, must be signed by the testator and by at least two competent witnesses who are present at the same time and observe the testator signing the will or acknowledging the will. A codicil is an amendment to a will that alters, adds to, or revokes a portion of the will and must meet the same legal requirements as the original will. It's important to note that wills do not take effect until the death of the testator and can be changed or revoked at any time before the testator's death. An attorney can provide specific guidance on creating a valid will and ensuring that it reflects the testator's intentions in accordance with Washington law.