From Wikipedia: A need is something that is necessary for organisms to live a healthy life. Needs are distinguished from wants because a deficiency would cause a clear negative outcome, such as dysfunction or death. Needs can be objective and physical, such as food, or they can be subjective and psychological, such as the need for self-esteem. On a social level, needs are sometimes controversial. Understanding needs and wants is an issue in the fields of politics, social science, and philosophy.