A need is a deficiency at a point of time and in a given context. Needs are distinguished from wants. In the case of a need, a deficiency causes a clear adverse outcome: a dysfunction or death. In other words, a need is something required for a safe, stable and healthy life (e.g. air, water, food, land, shelter) while a want is a desire, wish or aspiration. When needs or wants are backed by purchasing power, they have the potential to become economic demands.
Basic needs such as air, water, food and protection from environmental dangers are necessary for an organism to live. In addition to basic needs, humans also have needs of a social or societal nature such as the human need for purpose, to socialize, to belong to a family or community or other group. Needs can be objective and physical, such as the need for food, or psychical and subjective, such as the need for self-esteem. Understanding both kinds of "unmet needs" is improved by considering the social context of their not being fulfilled.
