This map shows the Average Male and Female Heights by Country. Human height or stature is the distance from the bottom of the feet to the top of the head in a human body, standing erect. It is measured using a stadiometer, usually in centimetres when using the metric system, or feet and inches when using the imperial system. When populations share genetic background and environmental factors, average height is frequently characteristic within the group. Exceptional height variation (around 20% deviation from average) within such a population is sometimes due to gigantism or dwarfism, which are medical conditions caused by specific genes or endocrine abnormalities. Height is considered an indication of a country's well-being. As the economy increases, so does the average height of the population. Wealth tends to improve nutrition and medical care. This enables younger people to reach their maximum growth potential and as a result to live longer.