A will is a legal document that describes how your assets should be distributed in the event of your death. The actual distribution; however, is controlled by a legal process called probate, which is Latin for "prove the will." Upon your death, the will becomes a public document available for anyone to review. Once your will enters the probate process, it is no longer controlled by your family, rather it is controlled by the court and probate attorneys.
If you die without a will, called intestate, the state determines who will be your ultimate heirs. A state created will often does not meet an individual's wishes as the court appoints a personal representative. State law determines the beneficiaries and no charitable distributions are allowed. In addition, dying without a will means added administrative costs and taxes (if applicable). A will allows you to alter the state's default plan to suit your personal preferences.
Aside from providing guidance to the court for distribution of your assets, a will may also designate a guardian for your minor children, designate an executor of your estate, provide for a child (e.g. stepchild, godchild, etc.), and give information about the care of your child.