Hair is an indicator of good health; it is an extension of the skin. Hair quality reflects a person's physical health. Trichology is the diagnosis and treatment of diseases and disorders of the human hair and scalp. Hair loss can cause great suffering, and there are many misconceptions about its reasons and treatment. There are some types of hair loss which can have a natural or spontaneous recovery. Excessive hair loss can often be a symptom of some other problem or variation in the metabolism of the body and for this reason, co-operation between the patient's doctor and the trichologist is often necessary.