A will generally is a document that is prepared by an attorney and follows the requirements of the state in which the person writing it resides. Most often, a will tells how a person wants his or her property to be distributed when that person dies. A will takes effect only when the person who created it dies.
It is possible for a person to have multiple wills prepared during his or her lifetime. Generally speaking, when a person has a new will prepared, there is language in the new will revoking the old will. This shows that a will is revocable during the lifetime of the person having it prepared. If a new will is prepared without revoking an old will, the probate court typically becomes involved to decide which provisions will be in effect.