The scientific name for baldness is alopecia. In the simplest of terms, it is typified by the absence of hair where hair would normally grow. It occurs in human beings as well as its closest cousins the primates. Baldness in human beings is usually of a progressive type, meaning that growth becomes increasingly sparse in a typical pattern (alopecia androgenetica). The total loss of hair (alopecia totalis) is a far more severe variant. When it does occur, there is no way of predicting at what rate it will happen, though hereditary factors play a role.

Contrary to commonly prevalent myths, baldness in humans is not caused by excessive intellectual activity, but the significance of emotional stress in the problem is still a gray area. It is also not in any way related to the lack of or excessive indulgence in sexual activity, nor are bald men somehow more sexually gifted than their hirsute counterparts.

The onset of baldness can affect people in vastly different ways. Some take it in their stride, positively associating it with maturity and the natural winding down of the metabolism. Others, especially people in show business or those afflicted with low self-esteem, view it as a major disaster that must be corrected or camouflaged at all costs. The efforts to cosmetically correct baldness date back to the earliest annals of recorded history. Wigs have been discovered in Egyptian sarcophagi, and the ancient Greeks expended an enormous amount of time and energy in developing futile potions to counter baldness.

Baldness does not necessarily develop for natural reasons. Certain kinds of baldness can also take place because of artificial obstruction or disruption of natural hair growth. Other common reasons are stress, diseases like diphtheria and psoriasis, the use of certain medicines like antidepressants, and medical interventions like chemotherapy.