What is a document that expresses the wishes of patients in case of terminal illness or an accident after which patients cannot express their wishes?

A document that expresses the wishes of patients in case of terminal illness or an accident is called an advance directive or living will. This legal document outlines a patient's preferences for medical treatment and interventions when they are unable to communicate their wishes due to incapacitation. It may also designate a healthcare proxy to make decisions on their behalf, ensuring that their values and preferences are respected.