First, a healthcare proxy appoints someone to make your medical decisions if you can't. A living will tells doctors what you want done if you're in a coma and will never recover. Finally, a HIPPA form allows doctors to release medical information to your health care proxy.
These documents are so important that many hospitals have people sign them when they are admitted. But if you are already unconscious when you go to the hospital and do not already have a plan in place, the doctors may make your medical decisions without your family's input.
A will, the fourth document in the basic plan, deals with decisions that have to be made once you pass. It will determine happens to your property, and, more importantly for many young couples, who will raise your children.
A will gives your family the power to liquidate your assets and distribute them to your heirs.