Human height is the distance from the bottom of the feet to the top of the head in a human body

Human body

The human body is the entire structure of a human organism, and consists of a head, neck, torso, two arms and two legs.By the time the human reaches adulthood, the body consists of close to 100 trillion cells, the basic unit of life...

 standing erect.

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 usually due to gigantism

Gigantism

Gigantism, also known as giantism , is a condition characterized by excessive growth and height significantly above average...

 or dwarfism

Dwarfism

Dwarfism is short stature resulting from a medical condition. It is sometimes defined as an adult height of less than 4 feet 10 inches  , although this definition is problematic because short stature in itself is not a disorder....

; which are medical conditions due to specific gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

s or to endocrine abnormalities.

In regions of extreme poverty or prolonged warfare, environmental factors like malnutrition during childhood or adolescence may account for marked reductions in adult stature even without the presence of any of these medical conditions.
The average height for each sex within a population varies significantly, with men being (on average) taller than women.